<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:01a0a529-f6fa-7f6d-b34e-f2ccd6708f13,g:1e332c87-eac3-46ed-8bc1-af029a1823fd-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="https://xbrl.org/2023/arcrole/summation-item" xlink:type="simple" xlink:href="https://www.xbrl.org/2023/calculation-1.1.xsd#summation-item"/>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITIONUnaudited" xlink:type="simple" xlink:href="nwbi-20260930.xsd#CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITIONUnaudited"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITIONUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7775-a991-6bfecaf80a5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_01a0a529-feb3-72ff-a754-30cd90005b83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7775-a991-6bfecaf80a5c" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_01a0a529-feb3-72ff-a754-30cd90005b83" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossAndLoansHeldForSale_01a0a529-feb3-79d6-ade4-676a181175e3" xlink:href="nwbi-20260930.xsd#nwbi_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossAndLoansHeldForSale"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7775-a991-6bfecaf80a5c" xlink:to="loc_nwbi_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossAndLoansHeldForSale_01a0a529-feb3-79d6-ade4-676a181175e3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_01a0a529-feb3-737b-a95a-80d599cc6560" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssets"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_OtherAssets_01a0a529-feb3-737b-a95a-80d599cc6560" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-73e9-8342-ecca2837bc96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-73e9-8342-ecca2837bc96" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableHeldForSaleAmount_01a0a529-feb3-78d1-b06b-67b75572aeaf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansReceivableHeldForSaleAmount"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_LoansReceivableHeldForSaleAmount_01a0a529-feb3-78d1-b06b-67b75572aeaf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_01a0a529-feb3-7366-81f3-f2d1c2f5e979" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_01a0a529-feb3-7366-81f3-f2d1c2f5e979" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_01a0a529-feb3-796a-b2ed-213c3ccfe5a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestReceivable"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_InterestReceivable_01a0a529-feb3-796a-b2ed-213c3ccfe5a2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalHomeLoanBankStock_01a0a529-feb3-7b27-84e5-3d1af7d12bba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalHomeLoanBankStock"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_FederalHomeLoanBankStock_01a0a529-feb3-7b27-84e5-3d1af7d12bba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_CashCashEquivalentsAndMarketableSecurities_01a0a529-feb3-731f-ae02-524d242718e8" xlink:href="nwbi-20260930.xsd#nwbi_CashCashEquivalentsAndMarketableSecurities"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_nwbi_CashCashEquivalentsAndMarketableSecurities_01a0a529-feb3-731f-ae02-524d242718e8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_01a0a529-feb3-785c-9e84-60e6a01c4462" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_Goodwill_01a0a529-feb3-785c-9e84-60e6a01c4462" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealEstateAcquiredThroughForeclosure_01a0a529-feb3-7129-a37d-dac1506803b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealEstateAcquiredThroughForeclosure"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_RealEstateAcquiredThroughForeclosure_01a0a529-feb3-7129-a37d-dac1506803b4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankOwnedLifeInsurance_01a0a529-feb3-7612-9c03-f9aff4e05e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BankOwnedLifeInsurance"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_BankOwnedLifeInsurance_01a0a529-feb3-7612-9c03-f9aff4e05e8d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_01a0a529-feb3-75df-92b9-dce07a33ede0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_01a0a529-feb3-7c1d-878b-b1c6a13996c5" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_01a0a529-feb3-75df-92b9-dce07a33ede0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_01a0a529-feb3-7296-aef1-d26c9b5c6f72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_01a0a529-feb3-7828-a8fd-7b93122fcc06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_01a0a529-feb3-7296-aef1-d26c9b5c6f72" xlink:to="loc_us-gaap_Liabilities_01a0a529-feb3-7828-a8fd-7b93122fcc06" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_01a0a529-feb3-72b5-97d2-b79d966af951" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_01a0a529-feb3-7296-aef1-d26c9b5c6f72" xlink:to="loc_us-gaap_StockholdersEquity_01a0a529-feb3-72b5-97d2-b79d966af951" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_01a0a529-feb3-707d-a655-89ce03b2ebdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubordinatedDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_us-gaap_SubordinatedDebt_01a0a529-feb3-707d-a655-89ce03b2ebdf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Deposits_01a0a529-feb3-7247-9f4b-92f949230031" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Deposits"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_us-gaap_Deposits_01a0a529-feb3-7247-9f4b-92f949230031" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtShortTermAndLongTerm_01a0a529-feb3-7516-8af7-cc81e6e82fd2" xlink:href="nwbi-20260930.xsd#nwbi_DebtShortTermAndLongTerm"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_nwbi_DebtShortTermAndLongTerm_01a0a529-feb3-7516-8af7-cc81e6e82fd2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_01a0a529-feb3-7fdc-ac6b-02976f29c2c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_01a0a529-feb3-7fdc-ac6b-02976f29c2c6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust_01a0a529-feb3-7e45-bb7e-da4490ebabe2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust_01a0a529-feb3-7e45-bb7e-da4490ebabe2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_01a0a529-feb3-74f8-868e-8e7829cc24fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilities"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_us-gaap_OtherLiabilities_01a0a529-feb3-74f8-868e-8e7829cc24fa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvancePaymentsByBorrowersForTaxesAndInsurance_01a0a529-feb3-77ba-a944-f41adc25d5f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdvancePaymentsByBorrowersForTaxesAndInsurance"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_01a0a529-feb3-73fa-b1a0-3788ecf5a9bf" xlink:to="loc_us-gaap_AdvancePaymentsByBorrowersForTaxesAndInsurance_01a0a529-feb3-77ba-a944-f41adc25d5f5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Deposits_01a0a529-feb3-781d-86a2-347473892190" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Deposits"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestBearingDomesticDepositChecking_01a0a529-feb3-70da-8cb2-e5d6118549db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestBearingDomesticDepositChecking"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Deposits_01a0a529-feb3-781d-86a2-347473892190" xlink:to="loc_us-gaap_InterestBearingDomesticDepositChecking_01a0a529-feb3-70da-8cb2-e5d6118549db" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestBearingDomesticDepositChecking_01a0a529-feb3-7544-99d0-b926b3574a25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestBearingDomesticDepositChecking"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Deposits_01a0a529-feb3-781d-86a2-347473892190" xlink:to="loc_us-gaap_NoninterestBearingDomesticDepositChecking_01a0a529-feb3-7544-99d0-b926b3574a25" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsMoneyMarketDeposits_01a0a529-feb3-7633-8a0a-137bdcd7d9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsMoneyMarketDeposits"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Deposits_01a0a529-feb3-781d-86a2-347473892190" xlink:to="loc_us-gaap_DepositsMoneyMarketDeposits_01a0a529-feb3-7633-8a0a-137bdcd7d9b6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsSavingsDeposits_01a0a529-feb3-7bf7-82c5-453adecb58ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsSavingsDeposits"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Deposits_01a0a529-feb3-781d-86a2-347473892190" xlink:to="loc_us-gaap_DepositsSavingsDeposits_01a0a529-feb3-7bf7-82c5-453adecb58ab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeDeposits_01a0a529-feb3-7443-a6ad-d854ec4daa11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TimeDeposits"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Deposits_01a0a529-feb3-781d-86a2-347473892190" xlink:to="loc_us-gaap_TimeDeposits_01a0a529-feb3-7443-a6ad-d854ec4daa11" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_CashCashEquivalentsAndMarketableSecurities_01a0a529-feb3-7163-93dc-138968c97d78" xlink:href="nwbi-20260930.xsd#nwbi_CashCashEquivalentsAndMarketableSecurities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_01a0a529-feb3-7dd0-8c11-1ce4b0b507cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_CashCashEquivalentsAndMarketableSecurities_01a0a529-feb3-7163-93dc-138968c97d78" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_01a0a529-feb3-7dd0-8c11-1ce4b0b507cc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-715f-b7ee-74506d800504" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_CashCashEquivalentsAndMarketableSecurities_01a0a529-feb3-7163-93dc-138968c97d78" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-715f-b7ee-74506d800504" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndDueFromBanks_01a0a529-feb3-70f6-91e9-f9d90524d901" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndDueFromBanks"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_CashCashEquivalentsAndMarketableSecurities_01a0a529-feb3-7163-93dc-138968c97d78" xlink:to="loc_us-gaap_CashAndDueFromBanks_01a0a529-feb3-70f6-91e9-f9d90524d901" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_01a0a529-feb3-7a3a-a6cf-cfdc18668f7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_01a0a529-feb3-7a9e-986d-31eebd585277" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_01a0a529-feb3-7a3a-a6cf-cfdc18668f7e" xlink:to="loc_us-gaap_PreferredStockValue_01a0a529-feb3-7a9e-986d-31eebd585277" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_01a0a529-feb3-77c9-8321-cc111f29aaef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_01a0a529-feb3-7a3a-a6cf-cfdc18668f7e" xlink:to="loc_us-gaap_CommonStockValue_01a0a529-feb3-77c9-8321-cc111f29aaef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_01a0a529-feb3-7ed4-bad3-c03f8b19913a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_01a0a529-feb3-7a3a-a6cf-cfdc18668f7e" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_01a0a529-feb3-7ed4-bad3-c03f8b19913a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_01a0a529-feb3-75a2-917e-00411c63b530" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_01a0a529-feb3-7a3a-a6cf-cfdc18668f7e" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_01a0a529-feb3-75a2-917e-00411c63b530" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_01a0a529-feb3-7c64-b41c-3829b525b884" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_01a0a529-feb3-7a3a-a6cf-cfdc18668f7e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_01a0a529-feb3-7c64-b41c-3829b525b884" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFINCOMEUnaudited" xlink:type="simple" xlink:href="nwbi-20260930.xsd#CONSOLIDATEDSTATEMENTSOFINCOMEUnaudited"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFINCOMEUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestIncome"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnSalesOfOtherRealEstate_01a0a529-feb3-7088-8a68-ae08c896f7c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnSalesOfOtherRealEstate"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_us-gaap_GainsLossesOnSalesOfOtherRealEstate_01a0a529-feb3-7088-8a68-ae08c896f7c3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_GainOnSaleOfSBALoansNet_01a0a529-feb3-75ef-b280-859065156e24" xlink:href="nwbi-20260930.xsd#nwbi_GainOnSaleOfSBALoansNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_nwbi_GainOnSaleOfSBALoansNet_01a0a529-feb3-75ef-b280-859065156e24" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankOwnedLifeInsuranceIncome_01a0a529-feb3-74ef-b2ef-010ef12596ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BankOwnedLifeInsuranceIncome"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_us-gaap_BankOwnedLifeInsuranceIncome_01a0a529-feb3-74ef-b2ef-010ef12596ec" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesGainLoss_01a0a529-feb3-7dde-af4f-9415fb84378a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndEquitySecuritiesGainLoss"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesGainLoss_01a0a529-feb3-7dde-af4f-9415fb84378a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_MortgageBankingIncome_01a0a529-feb3-7f3a-acc3-7bce8256d2ef" xlink:href="nwbi-20260930.xsd#nwbi_MortgageBankingIncome"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_nwbi_MortgageBankingIncome_01a0a529-feb3-7f3a-acc3-7bce8256d2ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncomeOtherOperatingIncome_01a0a529-feb3-7513-97c4-eaeea6256f70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestIncomeOtherOperatingIncome"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_us-gaap_NoninterestIncomeOtherOperatingIncome_01a0a529-feb3-7513-97c4-eaeea6256f70" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_01a0a529-feb3-7ac4-acff-6b99a2fb8163" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FeesAndCommissionsMortgageBankingAndServicing"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_01a0a529-feb3-7ac4-acff-6b99a2fb8163" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_FeesAndCommissionsTrustServicesAndOtherIncome_01a0a529-feb3-70c1-9ab6-7c233123e0ba" xlink:href="nwbi-20260930.xsd#nwbi_FeesAndCommissionsTrustServicesAndOtherIncome"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7116-95c4-582649aee417" xlink:to="loc_nwbi_FeesAndCommissionsTrustServicesAndOtherIncome_01a0a529-feb3-70c1-9ab6-7c233123e0ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a0a529-feb3-7781-8804-117e91f72156" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_01a0a529-feb3-7269-b08b-74120b51f5b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a0a529-feb3-7781-8804-117e91f72156" xlink:to="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_01a0a529-feb3-7269-b08b-74120b51f5b3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7b41-a428-41201457e7be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestIncome"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a0a529-feb3-7781-8804-117e91f72156" xlink:to="loc_us-gaap_NoninterestIncome_01a0a529-feb3-7b41-a428-41201457e7be" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestExpense_01a0a529-feb3-7e12-9c6a-e56fe7c13044" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestExpense"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a0a529-feb3-7781-8804-117e91f72156" xlink:to="loc_us-gaap_NoninterestExpense_01a0a529-feb3-7e12-9c6a-e56fe7c13044" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_01a0a529-feb3-7120-aa1d-6b4a181da131" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_01a0a529-feb3-78dd-9f07-4a321ee193b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_01a0a529-feb3-7120-aa1d-6b4a181da131" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_01a0a529-feb3-78dd-9f07-4a321ee193b1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLossesExpensed_01a0a529-feb3-7c1a-bd11-075f4c08a54d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProvisionForLoanLossesExpensed"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_01a0a529-feb3-7120-aa1d-6b4a181da131" xlink:to="loc_us-gaap_ProvisionForLoanLossesExpensed_01a0a529-feb3-7c1a-bd11-075f4c08a54d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForOtherCreditLosses_01a0a529-feb3-7a7d-a49b-4a8c36f16225" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProvisionForOtherCreditLosses"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_01a0a529-feb3-7120-aa1d-6b4a181da131" xlink:to="loc_us-gaap_ProvisionForOtherCreditLosses_01a0a529-feb3-7a7d-a49b-4a8c36f16225" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoninterestExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_01a0a529-feb3-7e95-a410-3ddcb50c1001" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_LaborAndRelatedExpense_01a0a529-feb3-7e95-a410-3ddcb50c1001" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OccupancyNet_01a0a529-feb3-7a07-af48-697e4623dbae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OccupancyNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_OccupancyNet_01a0a529-feb3-7a07-af48-697e4623dbae" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_01a0a529-feb3-7d5f-bceb-5b26b91dcd0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_01a0a529-feb3-7d5f-bceb-5b26b91dcd0b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_NoninterestExpenseCollectionOfReceivables_01a0a529-feb3-7659-af66-f1777290e11c" xlink:href="nwbi-20260930.xsd#nwbi_NoninterestExpenseCollectionOfReceivables"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_nwbi_NoninterestExpenseCollectionOfReceivables_01a0a529-feb3-7659-af66-f1777290e11c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InformationTechnologyAndDataProcessing_01a0a529-feb3-715f-b859-ad47a682824f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InformationTechnologyAndDataProcessing"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_InformationTechnologyAndDataProcessing_01a0a529-feb3-715f-b859-ad47a682824f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketingExpense_01a0a529-feb3-762f-ac48-a9a025f7bf00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketingExpense"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_MarketingExpense_01a0a529-feb3-762f-ac48-a9a025f7bf00" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_01a0a529-feb3-7b61-b1c5-d8068fc27dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfessionalFees"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_ProfessionalFees_01a0a529-feb3-7b61-b1c5-d8068fc27dd6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_01a0a529-feb3-728e-b0f2-daa2862c6474" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_01a0a529-feb3-728e-b0f2-daa2862c6474" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoninterestExpense_01a0a529-feb3-7efa-b6b6-e389f629f1e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNoninterestExpense"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_OtherNoninterestExpense_01a0a529-feb3-7efa-b6b6-e389f629f1e5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_MergerAssetDispositionAndRestructuringExpense_01a0a529-feb3-7be0-9aac-800fd9b95571" xlink:href="nwbi-20260930.xsd#nwbi_MergerAssetDispositionAndRestructuringExpense"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_nwbi_MergerAssetDispositionAndRestructuringExpense_01a0a529-feb3-7be0-9aac-800fd9b95571" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalDepositInsuranceCorporationPremiumExpense_01a0a529-feb3-7675-9f96-c42853a2d914" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalDepositInsuranceCorporationPremiumExpense"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_us-gaap_FederalDepositInsuranceCorporationPremiumExpense_01a0a529-feb3-7675-9f96-c42853a2d914" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_FederalDepositInsuranceCorporationPremiumExpenseNet_01a0a529-feb3-7a84-a6e1-01d864d947ff" xlink:href="nwbi-20260930.xsd#nwbi_FederalDepositInsuranceCorporationPremiumExpenseNet"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NoninterestExpense_01a0a529-feb3-75ec-ba0c-8ab5892ba7ed" xlink:to="loc_nwbi_FederalDepositInsuranceCorporationPremiumExpenseNet_01a0a529-feb3-7a84-a6e1-01d864d947ff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_01a0a529-feb3-7142-a8a9-96ad0c60aa60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7c65-a9ec-3f47259bf875" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDividendIncomeOperating"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestIncomeExpenseNet_01a0a529-feb3-7142-a8a9-96ad0c60aa60" xlink:to="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7c65-a9ec-3f47259bf875" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOperating_01a0a529-feb3-7dec-b0d0-eb018638488c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseOperating"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestIncomeExpenseNet_01a0a529-feb3-7142-a8a9-96ad0c60aa60" xlink:to="loc_us-gaap_InterestExpenseOperating_01a0a529-feb3-7dec-b0d0-eb018638488c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDividendIncomeOperating"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndFeeIncomeLoansAndLeases_01a0a529-feb3-72b2-bec4-9ab7cf235da0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndFeeIncomeLoansAndLeases"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:to="loc_us-gaap_InterestAndFeeIncomeLoansAndLeases_01a0a529-feb3-72b2-bec4-9ab7cf235da0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeSecuritiesMortgageBacked_01a0a529-feb3-7e07-a314-617c90cd615e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeSecuritiesMortgageBacked"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:to="loc_us-gaap_InterestIncomeSecuritiesMortgageBacked_01a0a529-feb3-7e07-a314-617c90cd615e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeSecuritiesTaxable_01a0a529-feb3-7aff-911d-74c89a540e50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeSecuritiesTaxable"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:to="loc_us-gaap_InterestIncomeSecuritiesTaxable_01a0a529-feb3-7aff-911d-74c89a540e50" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeSecuritiesTaxExempt_01a0a529-feb3-77a7-9546-a3255bd92e64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeSecuritiesTaxExempt"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:to="loc_us-gaap_InterestIncomeSecuritiesTaxExempt_01a0a529-feb3-77a7-9546-a3255bd92e64" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendIncomeOperating_01a0a529-feb3-7aa2-a0cb-732c5bb0a42e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendIncomeOperating"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:to="loc_us-gaap_DividendIncomeOperating_01a0a529-feb3-7aa2-a0cb-732c5bb0a42e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeDepositsWithFinancialInstitutions_01a0a529-feb3-7be6-97b7-b925adfb897d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeDepositsWithFinancialInstitutions"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a529-feb3-7cd7-8236-6010bc7657a8" xlink:to="loc_us-gaap_InterestIncomeDepositsWithFinancialInstitutions_01a0a529-feb3-7be6-97b7-b925adfb897d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOperating_01a0a529-feb3-7bc5-99ad-921c937c9fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseOperating"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDeposits_01a0a529-feb3-706f-ad42-233015daae62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseDeposits"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpenseOperating_01a0a529-feb3-7bc5-99ad-921c937c9fbd" xlink:to="loc_us-gaap_InterestExpenseDeposits_01a0a529-feb3-706f-ad42-233015daae62" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseBorrowings_01a0a529-feb3-75ce-9639-a5bb96004d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseBorrowings"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpenseOperating_01a0a529-feb3-7bc5-99ad-921c937c9fbd" xlink:to="loc_us-gaap_InterestExpenseBorrowings_01a0a529-feb3-75ce-9639-a5bb96004d4a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-7781-b581-66670cc989b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a0a529-feb3-72ee-87a0-3f170c8239ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-7781-b581-66670cc989b2" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a0a529-feb3-72ee-87a0-3f170c8239ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_01a0a529-feb3-755f-94dc-3a406e4b8516" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-7781-b581-66670cc989b2" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_01a0a529-feb3-755f-94dc-3a406e4b8516" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEUnaudited" xlink:type="simple" xlink:href="nwbi-20260930.xsd#CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEUnaudited"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7d92-bb23-740ba1157f5f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_01a0a529-feb3-7da1-9f69-e2501c539bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7d92-bb23-740ba1157f5f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_01a0a529-feb3-7da1-9f69-e2501c539bd3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax_01a0a529-feb3-7a62-91a9-35123dc14822" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7d92-bb23-740ba1157f5f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax_01a0a529-feb3-7a62-91a9-35123dc14822" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_01a0a529-feb3-7a1e-9846-af4b2a9a6446" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-76d5-9c57-4b4d88312478" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_01a0a529-feb3-7a1e-9846-af4b2a9a6446" xlink:to="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-76d5-9c57-4b4d88312478" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-feb3-7329-9c67-97694a8eeb25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_01a0a529-feb3-7a1e-9846-af4b2a9a6446" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-feb3-7329-9c67-97694a8eeb25" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-feb3-79eb-a73a-f2f941fb99cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent_01a0a529-feb3-7b3d-9506-3f47000aaa1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-feb3-79eb-a73a-f2f941fb99cc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent_01a0a529-feb3-7b3d-9506-3f47000aaa1e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7c49-804a-0ee898d62527" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-feb3-79eb-a73a-f2f941fb99cc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7c49-804a-0ee898d62527" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7f68-807f-59f7eb63d8e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-feb3-79eb-a73a-f2f941fb99cc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7f68-807f-59f7eb63d8e9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7683-af52-b56572436af8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_01a0a529-feb3-7f25-8e40-343c9d4df714" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7683-af52-b56572436af8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_01a0a529-feb3-7f25-8e40-343c9d4df714" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax_01a0a529-feb3-7636-925c-8fd55b6ffed2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_01a0a529-feb3-7683-af52-b56572436af8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax_01a0a529-feb3-7636-925c-8fd55b6ffed2" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited" xlink:type="simple" xlink:href="nwbi-20260930.xsd#CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeposits_01a0a529-feb3-7419-a098-1da4f96f6ccc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInDeposits"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:to="loc_us-gaap_IncreaseDecreaseInDeposits_01a0a529-feb3-7419-a098-1da4f96f6ccc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_01a0a529-feb3-74ab-b634-0229c4985969" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_01a0a529-feb3-74ab-b634-0229c4985969" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRepaymentsOfShortTermDebt_01a0a529-feb3-7aba-bf25-ec23887c2575" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromRepaymentsOfShortTermDebt"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:to="loc_us-gaap_ProceedsFromRepaymentsOfShortTermDebt_01a0a529-feb3-7aba-bf25-ec23887c2575" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance_01a0a529-feb3-7d15-9398-331849aac09f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:to="loc_us-gaap_IncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance_01a0a529-feb3-7d15-9398-331849aac09f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_01a0a529-feb3-7e91-9c07-08e62556b3a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDividends"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:to="loc_us-gaap_PaymentsOfDividends_01a0a529-feb3-7e91-9c07-08e62556b3a9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_01a0a529-feb3-7712-b53b-105e05926b54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-7d0d-9ddf-ac26cfc8a3b0" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_01a0a529-feb3-7712-b53b-105e05926b54" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_01a0a529-feb3-7aef-bf1c-12279997e3b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-782c-87af-53ad35acd502" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_01a0a529-feb3-7aef-bf1c-12279997e3b2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a0a529-feb3-782c-87af-53ad35acd502" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-78dc-98c5-c770d33a0bc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_01a0a529-feb3-7aef-bf1c-12279997e3b2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-78dc-98c5-c770d33a0bc5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-7892-b8cb-9d1eabc33c82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_01a0a529-feb3-7aef-bf1c-12279997e3b2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-7892-b8cb-9d1eabc33c82" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-7984-927e-862bc8703d6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_NetIncomeLoss_01a0a529-feb3-7984-927e-862bc8703d6a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_01a0a529-feb3-7ba8-932f-8198bc82e5a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_01a0a529-feb3-7ba8-932f-8198bc82e5a7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfInvestments_01a0a529-feb3-7b62-a9b0-830839cad003" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfInvestments"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_GainLossOnSaleOfInvestments_01a0a529-feb3-7b62-a9b0-830839cad003" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfOtherAssets_01a0a529-feb3-7e7e-990d-80da5de680d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfOtherAssets"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_GainLossOnSaleOfOtherAssets_01a0a529-feb3-7e7e-990d-80da5de680d0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfProperties_01a0a529-feb3-76ee-a2ab-dd9d44d8228c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfProperties"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_GainLossOnSaleOfProperties_01a0a529-feb3-76ee-a2ab-dd9d44d8228c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_GainLossOnSaleOfSmallBusinessAdministrationLoans_01a0a529-feb3-716b-a4a8-6264102bebfa" xlink:href="nwbi-20260930.xsd#nwbi_GainLossOnSaleOfSmallBusinessAdministrationLoans"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_nwbi_GainLossOnSaleOfSmallBusinessAdministrationLoans_01a0a529-feb3-716b-a4a8-6264102bebfa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNet_01a0a529-feb3-7eae-980e-cc550a586950" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationAmortizationAndAccretionNet"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNet_01a0a529-feb3-7eae-980e-cc550a586950" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_01a0a529-feb3-7955-b95e-e135b3829213" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_01a0a529-feb3-7955-b95e-e135b3829213" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_01a0a529-feb3-71d6-88c3-c577ba35814a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_01a0a529-feb3-71d6-88c3-c577ba35814a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_01a0a529-feb3-73f2-b98d-f722a12b7093" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_01a0a529-feb3-73f2-b98d-f722a12b7093" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_01a0a529-feb3-7f93-96ae-5f4aaa5d9420" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_ShareBasedCompensation_01a0a529-feb3-7f93-96ae-5f4aaa5d9420" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfRealEstate_01a0a529-feb3-7d31-9a3a-2309521fec53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfRealEstate"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_ImpairmentOfRealEstate_01a0a529-feb3-7d31-9a3a-2309521fec53" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_01a0a529-feb3-7fcf-bb44-92d88635d462" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_01a0a529-feb3-7fcf-bb44-92d88635d462" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale_01a0a529-feb3-7e72-8b28-208f6178508d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale"/>
    <link:calculationArc order="14" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale_01a0a529-feb3-7e72-8b28-208f6178508d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfLoansHeldForSale_01a0a529-feb3-7dee-b842-de29186f2a97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfLoansHeldForSale"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a0a529-feb3-78bd-bf7a-f8db0d293ab7" xlink:to="loc_us-gaap_ProceedsFromSaleOfLoansHeldForSale_01a0a529-feb3-7dee-b842-de29186f2a97" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt_01a0a529-feb3-7867-82e9-0961c43e30f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt_01a0a529-feb3-7867-82e9-0961c43e30f1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities_01a0a529-feb3-7ddc-b0a2-1b5799b00cc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities_01a0a529-feb3-7ddc-b0a2-1b5799b00cc3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities_01a0a529-feb3-73c8-b81e-02a5fb096f2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities_01a0a529-feb3-73c8-b81e-02a5fb096f2c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_01a0a529-feb3-791b-b568-03dda813e7f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_01a0a529-feb3-791b-b568-03dda813e7f7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLifeInsurancePolicies_01a0a529-feb3-778a-83ad-1353dadc6662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromLifeInsurancePolicies"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_ProceedsFromLifeInsurancePolicies_01a0a529-feb3-778a-83ad-1353dadc6662" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_OriginationsOfLoansReceivableHeldForInvestment_01a0a529-feb3-7a53-afe3-78ed7aec0d06" xlink:href="nwbi-20260930.xsd#nwbi_OriginationsOfLoansReceivableHeldForInvestment"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_nwbi_OriginationsOfLoansReceivableHeldForInvestment_01a0a529-feb3-7a53-afe3-78ed7aec0d06" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_ProceedsFromMaturitiesAndPrincipalReductionsOnLoans_01a0a529-feb3-7dc2-9a96-0e16c57f64bd" xlink:href="nwbi-20260930.xsd#nwbi_ProceedsFromMaturitiesAndPrincipalReductionsOnLoans"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_nwbi_ProceedsFromMaturitiesAndPrincipalReductionsOnLoans_01a0a529-feb3-7dc2-9a96-0e16c57f64bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock_01a0a529-feb3-7bf2-8b54-3f1d8b12bc84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock_01a0a529-feb3-7bf2-8b54-3f1d8b12bc84" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfForeclosedAssets_01a0a529-feb3-7d46-8c29-462d0f241990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfForeclosedAssets"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_ProceedsFromSaleOfForeclosedAssets_01a0a529-feb3-7d46-8c29-462d0f241990" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_01a0a529-feb3-7d9c-a63b-330d4c347c3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_01a0a529-feb3-7d9c-a63b-330d4c347c3b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_01a0c80b-35c0-7881-8e99-258f0b0d77d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a0a529-feb3-7bdc-bb03-6c67461fd02b" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_01a0c80b-35c0-7881-8e99-258f0b0d77d0" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/AcquisitionAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#AcquisitionAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/AcquisitionAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_01a0a529-feb3-7826-932c-f2bf91b33b8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_01a0a529-feb3-7148-9566-4f2ac2d4dade" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferred1_01a0a529-feb3-7826-932c-f2bf91b33b8e" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_01a0a529-feb3-7148-9566-4f2ac2d4dade" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_01a0a529-feb3-728d-9fa3-9290fc407f14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferred1_01a0a529-feb3-7826-932c-f2bf91b33b8e" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_01a0a529-feb3-728d-9fa3-9290fc407f14" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedDepositsLiabilities_01a0a529-feb3-7aaa-b749-ad821f181d98" xlink:href="nwbi-20260930.xsd#nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedDepositsLiabilities"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedDepositsLiabilities_01a0a529-feb3-7aaa-b749-ad821f181d98" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_01a0a529-feb3-70c8-8b7d-4f7ee31420cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_01a0a529-feb3-70c8-8b7d-4f7ee31420cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_01a0a529-feb3-7f44-9115-cfe6cb1da0c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_01a0a529-feb3-7f44-9115-cfe6cb1da0c5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities_01a0a529-feb3-7b02-9f80-387b85ede188" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities_01a0a529-feb3-7b02-9f80-387b85ede188" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_01a0a529-feb3-756a-9bef-4c45b38f7ca1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_01a0a529-feb3-756a-9bef-4c45b38f7ca1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_01a0a529-feb3-70ac-a899-dcddd7d98809" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_01a0a529-feb3-70ac-a899-dcddd7d98809" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFederalHomeLoanBankStock_01a0a529-feb3-7e7f-809f-fca2a4f8795b" xlink:href="nwbi-20260930.xsd#nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFederalHomeLoanBankStock"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFederalHomeLoanBankStock_01a0a529-feb3-7e7f-809f-fca2a4f8795b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBorrowings_01a0a529-feb3-74a9-a2f3-99288dbbe86d" xlink:href="nwbi-20260930.xsd#nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBorrowings"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBorrowings_01a0a529-feb3-74a9-a2f3-99288dbbe86d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_01a0a529-feb3-7c17-be96-aa04396db4a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_01a0a529-feb3-7c17-be96-aa04396db4a9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansReceivable_01a0a529-feb3-765d-8550-41f6ca5def5c" xlink:href="nwbi-20260930.xsd#nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansReceivable"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_01a0a529-feb3-72bd-b710-28998a411f3b" xlink:to="loc_nwbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansReceivable_01a0a529-feb3-765d-8550-41f6ca5def5c" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/AcquisitionLoanPortfolioatAcquisitionDateDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#AcquisitionLoanPortfolioatAcquisitionDateDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/AcquisitionLoanPortfolioatAcquisitionDateDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7602-be31-9f6e2ae06727" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess_01a0a529-feb3-751c-9193-e6d1643a65af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7602-be31-9f6e2ae06727" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess_01a0a529-feb3-751c-9193-e6d1643a65af" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount_01a0a529-feb3-7667-b4f3-1d3eabebd9a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7602-be31-9f6e2ae06727" xlink:to="loc_us-gaap_FinancingReceivableUnamortizedPurchasePremiumDiscount_01a0a529-feb3-7667-b4f3-1d3eabebd9a5" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/MarketableSecuritiesAvailableforSaleDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#MarketableSecuritiesAvailableforSaleDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/MarketableSecuritiesAvailableforSaleDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_01a0a529-feb3-741b-8071-8818c04d167e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleAfterFiveThroughTenYearsGrossUnrealizedGain_01a0a529-feb3-7ae8-b04e-3c648ff723e9" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleAfterFiveThroughTenYearsGrossUnrealizedGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_01a0a529-feb3-741b-8071-8818c04d167e" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleAfterFiveThroughTenYearsGrossUnrealizedGain_01a0a529-feb3-7ae8-b04e-3c648ff723e9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7e8d-9f28-795c5dc78f33" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_01a0a529-feb3-741b-8071-8818c04d167e" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7e8d-9f28-795c5dc78f33" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleAfterFiveThroughTenYearsGrossUnrealizedLoss_01a0a529-feb3-7570-a648-aab23b9fe5ef" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleAfterFiveThroughTenYearsGrossUnrealizedLoss"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_01a0a529-feb3-741b-8071-8818c04d167e" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleAfterFiveThroughTenYearsGrossUnrealizedLoss_01a0a529-feb3-7570-a648-aab23b9fe5ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7ca8-888a-4f5b51a6741d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_01a0a529-feb3-71cd-bbc7-0c1d4db65294" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7ca8-888a-4f5b51a6741d" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_01a0a529-feb3-71cd-bbc7-0c1d4db65294" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_01a0a529-feb3-7ac4-98d7-ad199b6d0b17" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7ca8-888a-4f5b51a6741d" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_01a0a529-feb3-7ac4-98d7-ad199b6d0b17" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_01a0a529-feb3-7500-808e-7e766f261f21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-feb3-7ca8-888a-4f5b51a6741d" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_01a0a529-feb3-7500-808e-7e766f261f21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_01a0a529-feb3-75d9-8b7c-100406d78533" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleAfterOneThroughFiveYearsGrossUnrealizedGain_01a0a529-feb3-7223-8fc5-4460e4a4eedb" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleAfterOneThroughFiveYearsGrossUnrealizedGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_01a0a529-feb3-75d9-8b7c-100406d78533" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleAfterOneThroughFiveYearsGrossUnrealizedGain_01a0a529-feb3-7223-8fc5-4460e4a4eedb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-7175-98e4-5698bd1dfc0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_01a0a529-feb3-75d9-8b7c-100406d78533" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-7175-98e4-5698bd1dfc0b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleAfterOneThroughFiveYearsGrossUnrealizedLoss_01a0a529-feb3-7717-a13f-3b1aad69d452" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleAfterOneThroughFiveYearsGrossUnrealizedLoss"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_01a0a529-feb3-75d9-8b7c-100406d78533" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleAfterOneThroughFiveYearsGrossUnrealizedLoss_01a0a529-feb3-7717-a13f-3b1aad69d452" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_01a0a529-feb3-7b8f-a2a4-cf8a5fd96b0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleOneYearOrLessGrossUnrealizedGain_01a0a529-feb3-7f6e-be13-90e26a6408bb" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleOneYearOrLessGrossUnrealizedGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_01a0a529-feb3-7b8f-a2a4-cf8a5fd96b0a" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleOneYearOrLessGrossUnrealizedGain_01a0a529-feb3-7f6e-be13-90e26a6408bb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleOneYearOrLessGrossUnrealizedLoss_01a0a529-feb3-7e2f-b359-2a0fb22cc5e7" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleOneYearOrLessGrossUnrealizedLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_01a0a529-feb3-7b8f-a2a4-cf8a5fd96b0a" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleOneYearOrLessGrossUnrealizedLoss_01a0a529-feb3-7e2f-b359-2a0fb22cc5e7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_01a0a529-feb3-7207-b6ed-bc4af863a970" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_01a0a529-feb3-7b8f-a2a4-cf8a5fd96b0a" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_01a0a529-feb3-7207-b6ed-bc4af863a970" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_01a0a529-feb3-75b6-a618-996d54f72385" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleAfterTenYearsGrossUnrealizedGain_01a0a529-feb3-7b93-b4e5-7e208ea739f9" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleAfterTenYearsGrossUnrealizedGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_01a0a529-feb3-75b6-a618-996d54f72385" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleAfterTenYearsGrossUnrealizedGain_01a0a529-feb3-7b93-b4e5-7e208ea739f9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_01a0a529-feb3-7b52-a230-1a0b7e8c70b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_01a0a529-feb3-75b6-a618-996d54f72385" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_01a0a529-feb3-7b52-a230-1a0b7e8c70b6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesAvailableForSaleAfterTenYearsGrossUnrealizedLoss_01a0a529-feb3-7d4a-9b21-d89a87889ee9" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesAvailableForSaleAfterTenYearsGrossUnrealizedLoss"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_01a0a529-feb3-75b6-a618-996d54f72385" xlink:to="loc_nwbi_DebtSecuritiesAvailableForSaleAfterTenYearsGrossUnrealizedLoss_01a0a529-feb3-7d4a-9b21-d89a87889ee9" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/MarketableSecuritiesHeldtoMaturityDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#MarketableSecuritiesHeldtoMaturityDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/MarketableSecuritiesHeldtoMaturityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_01a0a529-feb3-7878-a79b-cd03fda2ca96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesHeldToMaturityAfterOneThroughFiveYearsGrossUnrealizedGain_01a0a529-feb3-7c84-8037-fa9ad479d6ef" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesHeldToMaturityAfterOneThroughFiveYearsGrossUnrealizedGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_01a0a529-feb3-7878-a79b-cd03fda2ca96" xlink:to="loc_nwbi_DebtSecuritiesHeldToMaturityAfterOneThroughFiveYearsGrossUnrealizedGain_01a0a529-feb3-7c84-8037-fa9ad479d6ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-733d-8e9d-9d931b4dbd9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_01a0a529-feb3-7878-a79b-cd03fda2ca96" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-733d-8e9d-9d931b4dbd9e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesHeldToMaturityAfterOneThroughFiveYearsGrossUnrealizedLoss_01a0a529-feb3-7e87-8ff7-adafb927cadc" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesHeldToMaturityAfterOneThroughFiveYearsGrossUnrealizedLoss"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_01a0a529-feb3-7878-a79b-cd03fda2ca96" xlink:to="loc_nwbi_DebtSecuritiesHeldToMaturityAfterOneThroughFiveYearsGrossUnrealizedLoss_01a0a529-feb3-7e87-8ff7-adafb927cadc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7faf-ba9c-b81745c921c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_01a0a529-feb3-7d13-a2f5-f212f95df1a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7faf-ba9c-b81745c921c0" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_01a0a529-feb3-7d13-a2f5-f212f95df1a7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_01a0a529-feb3-7ff5-9221-d214fa1a912d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7faf-ba9c-b81745c921c0" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_01a0a529-feb3-7ff5-9221-d214fa1a912d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_01a0a529-feb3-7aeb-baf7-1096f24ceade" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_01a0a529-feb3-7faf-ba9c-b81745c921c0" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_01a0a529-feb3-7aeb-baf7-1096f24ceade" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_01a0a529-feb3-7c3b-b9d9-ea7677004a46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesHeldToMaturityAfterFiveThroughTenYearsGrossUnrealizedGain_01a0a529-feb3-720c-a23a-0cd8e0a745fc" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesHeldToMaturityAfterFiveThroughTenYearsGrossUnrealizedGain"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_01a0a529-feb3-7c3b-b9d9-ea7677004a46" xlink:to="loc_nwbi_DebtSecuritiesHeldToMaturityAfterFiveThroughTenYearsGrossUnrealizedGain_01a0a529-feb3-720c-a23a-0cd8e0a745fc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_DebtSecuritiesHeldToMaturityAfterFiveThroughTenYearsGrossUnrealizedLoss_01a0a529-feb3-75d3-bcf2-19f6e13c2a54" xlink:href="nwbi-20260930.xsd#nwbi_DebtSecuritiesHeldToMaturityAfterFiveThroughTenYearsGrossUnrealizedLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_01a0a529-feb3-7c3b-b9d9-ea7677004a46" xlink:to="loc_nwbi_DebtSecuritiesHeldToMaturityAfterFiveThroughTenYearsGrossUnrealizedLoss_01a0a529-feb3-75d3-bcf2-19f6e13c2a54" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7e3c-bb57-a51a7f5b4931" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_01a0a529-feb3-7c3b-b9d9-ea7677004a46" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7e3c-bb57-a51a7f5b4931" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/MarketableSecuritiesAvailableforSalebyContractualMaturityDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#MarketableSecuritiesAvailableforSalebyContractualMaturityDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/MarketableSecuritiesAvailableforSalebyContractualMaturityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-7598-b378-6f2b9ece36ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_01a0a529-feb3-7a68-b93d-7ff23270fb6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-7598-b378-6f2b9ece36ca" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost_01a0a529-feb3-7a68-b93d-7ff23270fb6d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_01a0a529-feb3-72c5-9622-20d9f3996ff1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-7598-b378-6f2b9ece36ca" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost_01a0a529-feb3-72c5-9622-20d9f3996ff1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_01a0a529-feb3-763a-8b24-9ea04fa3eb68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-7598-b378-6f2b9ece36ca" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost_01a0a529-feb3-763a-8b24-9ea04fa3eb68" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_01a0a529-feb3-7635-a8e2-37c1cae02315" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-7598-b378-6f2b9ece36ca" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost_01a0a529-feb3-7635-a8e2-37c1cae02315" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate_01a0a529-feb3-795d-a566-0b4a49e12832" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-7809-8117-adb6cff855da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate_01a0a529-feb3-795d-a566-0b4a49e12832" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-7809-8117-adb6cff855da" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_01a0a529-feb3-78f9-8bd1-c77056fab223" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate_01a0a529-feb3-795d-a566-0b4a49e12832" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_01a0a529-feb3-78f9-8bd1-c77056fab223" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_01a0a529-feb3-75b1-b2ff-8ad795eb1427" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate_01a0a529-feb3-795d-a566-0b4a49e12832" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_01a0a529-feb3-75b1-b2ff-8ad795eb1427" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7e7f-9b2f-81ae143c49b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate_01a0a529-feb3-795d-a566-0b4a49e12832" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7e7f-9b2f-81ae143c49b2" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/MarketableSecuritiesHeldtoMaturitybyContractualMaturityDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#MarketableSecuritiesHeldtoMaturitybyContractualMaturityDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/MarketableSecuritiesHeldtoMaturitybyContractualMaturityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-78c9-81e7-4526f00a4f9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_01a0a529-feb3-7680-9141-bb2e5203a1ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-78c9-81e7-4526f00a4f9e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount_01a0a529-feb3-7680-9141-bb2e5203a1ea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_01a0a529-feb3-7bcd-b54a-33e6733a65fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-78c9-81e7-4526f00a4f9e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount_01a0a529-feb3-7bcd-b54a-33e6733a65fa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount_01a0a529-feb3-7459-9bc7-4688e6546512" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis_01a0a529-feb3-78c9-81e7-4526f00a4f9e" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount_01a0a529-feb3-7459-9bc7-4688e6546512" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue_01a0a529-feb3-7838-a7c7-7faca7eafc25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7b12-9d54-a18e32272abe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue_01a0a529-feb3-7838-a7c7-7faca7eafc25" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_01a0a529-feb3-7b12-9d54-a18e32272abe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue_01a0a529-feb3-7c93-bc24-3654b81b2597" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue_01a0a529-feb3-7838-a7c7-7faca7eafc25" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue_01a0a529-feb3-7c93-bc24-3654b81b2597" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-74dc-9e20-62da4c495787" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue_01a0a529-feb3-7838-a7c7-7faca7eafc25" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_01a0a529-feb3-74dc-9e20-62da4c495787" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/MarketableSecuritiesFairValueofandGrossUnrealizedLossesonInvestmentSecuritiesDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#MarketableSecuritiesFairValueofandGrossUnrealizedLossesonInvestmentSecuritiesDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/MarketableSecuritiesFairValueofandGrossUnrealizedLossesonInvestmentSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_01a0a529-feb3-7190-b74d-e5c0d4ca73bf" xlink:href="nwbi-20260930.xsd#nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_01a0a529-feb3-7abc-8b24-ad278c2e2baf" xlink:href="nwbi-20260930.xsd#nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_01a0a529-feb3-7190-b74d-e5c0d4ca73bf" xlink:to="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_01a0a529-feb3-7abc-8b24-ad278c2e2baf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_01a0a529-feb3-754f-8045-5be614de5fcf" xlink:href="nwbi-20260930.xsd#nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue_01a0a529-feb3-7190-b74d-e5c0d4ca73bf" xlink:to="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_01a0a529-feb3-754f-8045-5be614de5fcf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_01a0a529-feb3-78e4-87e5-58db64294e8c" xlink:href="nwbi-20260930.xsd#nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses_01a0a529-feb3-7c55-9eb8-77fa72d6ae82" xlink:href="nwbi-20260930.xsd#nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_01a0a529-feb3-78e4-87e5-58db64294e8c" xlink:to="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses_01a0a529-feb3-7c55-9eb8-77fa72d6ae82" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses_01a0a529-feb3-7108-8092-1cf2d7ccc5e3" xlink:href="nwbi-20260930.xsd#nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses_01a0a529-feb3-78e4-87e5-58db64294e8c" xlink:to="loc_nwbi_HeldToMaturityAndAvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses_01a0a529-feb3-7108-8092-1cf2d7ccc5e3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/LoansReceivableCreditQualityIndicatorsDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#LoansReceivableCreditQualityIndicatorsDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/LoansReceivableCreditQualityIndicatorsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_01a0a529-ff88-753b-acff-50ca9aacecac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_01a0a529-ff88-753b-acff-50ca9aacecac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_01a0a529-ff88-76a5-8e40-457e1ffeeb8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_01a0a529-ff88-76a5-8e40-457e1ffeeb8b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-7202-a980-aab8a95bda85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-7202-a980-aab8a95bda85" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-7b32-9b0b-4f37c573b321" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-7b32-9b0b-4f37c573b321" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-7b8a-bb45-ca99c1b30b80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-7b8a-bb45-ca99c1b30b80" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-75d0-9871-928844dc09a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-75d0-9871-928844dc09a6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-77a1-bc74-b7eb1de0f8ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_01a0a529-ff88-77a1-bc74-b7eb1de0f8ad" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_01a0a529-ff88-7245-b8f7-1215d9e29252" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_01a0a529-ff88-78a2-b607-9247f0e77dbf" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_01a0a529-ff88-7245-b8f7-1215d9e29252" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_01a0a529-ff88-7473-b553-7ef71ea94dd7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_01a0a529-ff88-7473-b553-7ef71ea94dd7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_01a0a529-ff88-755c-a942-efe628e34624" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_01a0a529-ff88-755c-a942-efe628e34624" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_01a0a529-ff88-763f-9224-900220561bf3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_01a0a529-ff88-763f-9224-900220561bf3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_01a0a529-ff88-787d-a99a-d3140c2919ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_01a0a529-ff88-787d-a99a-d3140c2919ca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_01a0a529-ff88-7888-9c21-04a5b0c614a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_01a0a529-ff88-7888-9c21-04a5b0c614a2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_01a0a529-ff88-72f1-8c0b-6dd926755414" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_01a0a529-ff88-72f1-8c0b-6dd926755414" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_01a0a529-ff88-7fb9-aee8-9f47b93fcb88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolving"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_01a0a529-ff88-7fb9-aee8-9f47b93fcb88" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_01a0a529-ff88-788e-a3c2-ea44a61ba0f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_01a0a529-ff88-7fc8-a788-11cadfd725d3" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_01a0a529-ff88-788e-a3c2-ea44a61ba0f5" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/GoodwillandOtherIntangibleAssetsIntangibleAssetsDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#GoodwillandOtherIntangibleAssetsIntangibleAssetsDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/GoodwillandOtherIntangibleAssetsIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_01a0a529-ff88-7960-86eb-2864d0c786b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_01a0a529-ff88-7b28-8bcb-0b876d79ccbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_01a0a529-ff88-7960-86eb-2864d0c786b2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_01a0a529-ff88-7b28-8bcb-0b876d79ccbc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_FiniteLivedIntangibleAssetsAcquisitionDisposition_01a0a529-ff88-7f1b-b129-6410c31fa309" xlink:href="nwbi-20260930.xsd#nwbi_FiniteLivedIntangibleAssetsAcquisitionDisposition"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_01a0a529-ff88-7960-86eb-2864d0c786b2" xlink:to="loc_nwbi_FiniteLivedIntangibleAssetsAcquisitionDisposition_01a0a529-ff88-7f1b-b129-6410c31fa309" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_01a0a529-ff88-7464-98d1-9fdd9b5cc0f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_01a0a529-ff88-7960-86eb-2864d0c786b2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_01a0a529-ff88-7464-98d1-9fdd9b5cc0f3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/EarningsPerShareDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#EarningsPerShareDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/EarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_01a0a529-ff88-7dc3-806f-70c446b3e074" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a529-ff88-7e50-87df-b826975a2a4d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_01a0a529-ff88-7dc3-806f-70c446b3e074" xlink:to="loc_us-gaap_NetIncomeLoss_01a0a529-ff88-7e50-87df-b826975a2a4d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_01a0a529-ff88-7b9c-a829-e8ba3ff63786" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_01a0a529-ff88-7dc3-806f-70c446b3e074" xlink:to="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_01a0a529-ff88-7b9c-a829-e8ba3ff63786" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_01a0a529-ff88-7f25-b022-9ed90a3bc966" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_01a0a529-ff88-7918-9c55-f9ec1a36d1c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_01a0a529-ff88-7f25-b022-9ed90a3bc966" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_01a0a529-ff88-7918-9c55-f9ec1a36d1c9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_01a0a529-ff88-77c8-880e-0e60ba57f972" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_01a0a529-ff88-7f25-b022-9ed90a3bc966" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_01a0a529-ff88-77c8-880e-0e60ba57f972" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_01a0a529-ff88-7db7-8f64-83c4b069be4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a529-ff88-7466-a75c-80477db06921" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_01a0a529-ff88-7db7-8f64-83c4b069be4a" xlink:to="loc_us-gaap_NetIncomeLoss_01a0a529-ff88-7466-a75c-80477db06921" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_01a0a529-ff88-75a6-84f5-0c3e8ddfaa6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_01a0a529-ff88-7db7-8f64-83c4b069be4a" xlink:to="loc_us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarningsLossBasic_01a0a529-ff88-75a6-84f5-0c3e8ddfaa6a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/PensionandOtherPostRetirementBenefitsDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#PensionandOtherPostRetirementBenefitsDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/PensionandOtherPostRetirementBenefitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01a0a529-ff88-73a3-a8c6-e1b7d5746ac7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_01a0a529-ff88-7553-bbdc-f1dea0345642" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01a0a529-ff88-73a3-a8c6-e1b7d5746ac7" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_01a0a529-ff88-7553-bbdc-f1dea0345642" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_01a0a529-ff88-7cf5-920f-cb305d020dfa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01a0a529-ff88-73a3-a8c6-e1b7d5746ac7" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_01a0a529-ff88-7cf5-920f-cb305d020dfa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_01a0a529-ff88-7922-bde0-39d0927182f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01a0a529-ff88-73a3-a8c6-e1b7d5746ac7" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_01a0a529-ff88-7922-bde0-39d0927182f6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_01a0a529-ff88-7f8e-81ce-7e1520758e62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01a0a529-ff88-73a3-a8c6-e1b7d5746ac7" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_01a0a529-ff88-7f8e-81ce-7e1520758e62" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_01a0a529-ff88-7a58-be50-1509d264c394" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01a0a529-ff88-73a3-a8c6-e1b7d5746ac7" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_01a0a529-ff88-7a58-be50-1509d264c394" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/DisclosuresAboutFairValueofFinancialInstrumentsCarryingAmountandEstimatedFairValueofFinancialInstrumentsDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#DisclosuresAboutFairValueofFinancialInstrumentsCarryingAmountandEstimatedFairValueofFinancialInstrumentsDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/DisclosuresAboutFairValueofFinancialInstrumentsCarryingAmountandEstimatedFairValueofFinancialInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoaned_01a0a529-ff88-75db-aaaa-69da3c042a48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritiesLoaned"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedGrossIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7b4e-97a3-644cc1514bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritiesLoanedGrossIncludingNotSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_SecuritiesLoaned_01a0a529-ff88-75db-aaaa-69da3c042a48" xlink:to="loc_us-gaap_SecuritiesLoanedGrossIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7b4e-97a3-644cc1514bf7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedAsset_01a0a529-ff88-7a18-be61-1aa9ab37c2fb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritiesLoanedAsset"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_SecuritiesLoaned_01a0a529-ff88-75db-aaaa-69da3c042a48" xlink:to="loc_us-gaap_SecuritiesLoanedAsset_01a0a529-ff88-7a18-be61-1aa9ab37c2fb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubordinatedDebt_01a0a529-ff88-775b-89b0-96a573addc72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubordinatedDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_SubordinatedDebt_01a0a529-ff88-775b-89b0-96a573addc72" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-7abc-b5b4-d3c316c1acb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-7abc-b5b4-d3c316c1acb7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-774a-8bbc-6371f472ffdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-774a-8bbc-6371f472ffdd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoaned_01a0a529-ff88-71f9-94d8-c2f540644811" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritiesLoaned"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_SecuritiesLoaned_01a0a529-ff88-71f9-94d8-c2f540644811" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesFairValueDisclosure_01a0a529-ff88-7016-b33b-7a113302b645" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesFairValueDisclosure"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_AccruedLiabilitiesFairValueDisclosure_01a0a529-ff88-7016-b33b-7a113302b645" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_SavingsAndDemandDeposits_01a0a529-ff88-7227-9418-7767c8fb3edc" xlink:href="nwbi-20260930.xsd#nwbi_SavingsAndDemandDeposits"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_nwbi_SavingsAndDemandDeposits_01a0a529-ff88-7227-9418-7767c8fb3edc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedGrossIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7fa0-84a4-63922d2d62ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritiesLoanedGrossIncludingNotSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_SecuritiesLoanedGrossIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7fa0-84a4-63922d2d62ed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsFairValueDisclosure_01a0a529-ff88-769b-b0c5-906db079c4f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsFairValueDisclosure"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_DepositsFairValueDisclosure_01a0a529-ff88-769b-b0c5-906db079c4f1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust_01a0a529-ff88-7e37-9e35-04162a976134" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_01a0a529-ff88-72a2-bc64-ceaefa5bc7e3" xlink:to="loc_us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust_01a0a529-ff88-7e37-9e35-04162a976134" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_01a0a529-ff88-7215-9942-34cbcb3ff361" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestReceivable"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_InterestReceivable_01a0a529-ff88-7215-9942-34cbcb3ff361" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_01a0a529-ff88-786c-83b3-bfd87b2f0ca0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_01a0a529-ff88-786c-83b3-bfd87b2f0ca0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_01a0a529-ff88-7499-a4c3-a909bb321943" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_DerivativeAssets_01a0a529-ff88-7499-a4c3-a909bb321943" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_01a0a529-ff88-76ad-8099-5ead512e45f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_01a0a529-ff88-76ad-8099-5ead512e45f6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure_01a0a529-ff88-7eab-bcd9-2717bd135f3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_InvestmentInFederalHomeLoanBankStockFairValueDisclosure_01a0a529-ff88-7eab-bcd9-2717bd135f3a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_01a0a529-ff88-7e01-bb90-b9c87b84af81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_01a0a529-ff88-7e01-bb90-b9c87b84af81" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_01a0a529-ff88-7067-a6fa-50314f8a68d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_01a0a529-ff88-7067-a6fa-50314f8a68d2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansHeldForSaleFairValueDisclosure_01a0a529-ff88-7407-90c3-5f1b8f43211c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansHeldForSaleFairValueDisclosure"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_LoansHeldForSaleFairValueDisclosure_01a0a529-ff88-7407-90c3-5f1b8f43211c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-71a3-b5a3-d4daeb5cc1be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-75de-b7d2-5a6d63e2f1cb" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-71a3-b5a3-d4daeb5cc1be" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/DisclosuresAboutFairValueofFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#DisclosuresAboutFairValueofFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/DisclosuresAboutFairValueofFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-78e7-8739-894bd9ee7b7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7ff5-8e28-854f61328a66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-78e7-8739-894bd9ee7b7a" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7ff5-8e28-854f61328a66" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_01a0a529-ff88-7e26-a1f7-fce676cdfce3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-78e7-8739-894bd9ee7b7a" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_01a0a529-ff88-7e26-a1f7-fce676cdfce3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset_01a0a529-ff88-70e6-91af-8692fe1c7eb6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_01a0a529-ff88-73b8-a719-a4c3611fbb9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset_01a0a529-ff88-70e6-91af-8692fe1c7eb6" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_01a0a529-ff88-73b8-a719-a4c3611fbb9b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuritiesLoanedAsset_01a0a529-ff88-7a7e-9c3c-4d2426942b27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuritiesLoanedAsset"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedAsset_01a0a529-ff88-70e6-91af-8692fe1c7eb6" xlink:to="loc_us-gaap_SecuritiesLoanedAsset_01a0a529-ff88-7a7e-9c3c-4d2426942b27" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-7b27-8139-d4607ab7ae49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_01a0a529-ff88-7f9b-8fd0-558d77efd144" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-7b27-8139-d4607ab7ae49" xlink:to="loc_us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure_01a0a529-ff88-7f9b-8fd0-558d77efd144" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_01a0a529-ff88-78a2-8646-b21c5675f42d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-7b27-8139-d4607ab7ae49" xlink:to="loc_us-gaap_DerivativeAssets_01a0a529-ff88-78a2-8646-b21c5675f42d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_01a0a529-ff88-7b5b-a2c4-15a674e154f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_01a0a529-ff88-7b27-8139-d4607ab7ae49" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_01a0a529-ff88-7b5b-a2c4-15a674e154f1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_01a0a529-ff88-7458-ab87-4045ac890ecf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_01a0a529-ff88-7e7f-86ee-323e53dfee39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssets_01a0a529-ff88-7458-ab87-4045ac890ecf" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_01a0a529-ff88-7e7f-86ee-323e53dfee39" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7b28-842c-86aab0878128" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssets_01a0a529-ff88-7458-ab87-4045ac890ecf" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_01a0a529-ff88-7b28-842c-86aab0878128" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_01a0a529-ff88-7b1b-9b7a-06d70453d9d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-7b08-9838-05809c900f52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_01a0a529-ff88-7b1b-9b7a-06d70453d9d5" xlink:to="loc_us-gaap_DerivativeLiabilities_01a0a529-ff88-7b08-9838-05809c900f52" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/DerivativeFinancialInstrumentsOffsettingAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#DerivativeFinancialInstrumentsOffsettingAssetsandLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/DerivativeFinancialInstrumentsOffsettingAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_01a0a529-ff88-71b4-96e7-679e3b7defcd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_01a0a529-ff88-7d54-8711-fa415686a8fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_01a0a529-ff88-71b4-96e7-679e3b7defcd" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_01a0a529-ff88-7d54-8711-fa415686a8fe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_01a0a529-ff88-7c9e-9629-f2ce690059fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_01a0a529-ff88-71b4-96e7-679e3b7defcd" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_01a0a529-ff88-7c9e-9629-f2ce690059fc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_01a0a529-ff88-7b02-9992-bd0945d18c83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_01a0a529-ff88-7b34-b44e-3b9c903e7526" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_01a0a529-ff88-7b02-9992-bd0945d18c83" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_01a0a529-ff88-7b34-b44e-3b9c903e7526" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_01a0a529-ff88-7504-9287-ef8b07f4330c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_01a0a529-ff88-7b02-9992-bd0945d18c83" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_01a0a529-ff88-7504-9287-ef8b07f4330c" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/ChangesinAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#ChangesinAccumulatedOtherComprehensiveIncomeDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/ChangesinAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-ff88-7f04-8034-b22fd0876e97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_01a0a529-ff88-74ba-8f1d-fb862b54820d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-ff88-7f04-8034-b22fd0876e97" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_01a0a529-ff88-74ba-8f1d-fb862b54820d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_01a0a529-ff88-723f-891f-9c25374e3d62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a0a529-ff88-7f04-8034-b22fd0876e97" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_01a0a529-ff88-723f-891f-9c25374e3d62" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.northwestsavingsbank.com/role/SegmentInformationDetails" xlink:type="simple" xlink:href="nwbi-20260930.xsd#SegmentInformationDetails"/>
  <link:calculationLink xlink:role="http://www.northwestsavingsbank.com/role/SegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_01a0a52a-004c-7161-ad27-0bca86c37e85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a52a-004c-7c57-9b0b-c0a395bf77c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndDividendIncomeOperating"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_01a0a52a-004c-7161-ad27-0bca86c37e85" xlink:to="loc_us-gaap_InterestAndDividendIncomeOperating_01a0a52a-004c-7c57-9b0b-c0a395bf77c6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_01a0a52a-004c-71c5-b99d-027833792071" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FeesAndCommissionsMortgageBankingAndServicing"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_01a0a52a-004c-7161-ad27-0bca86c37e85" xlink:to="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_01a0a52a-004c-71c5-b99d-027833792071" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_FeesAndCommissionsTrustServicesAndOtherIncome_01a0a52a-004c-7e9f-990b-58e40d75ca4f" xlink:href="nwbi-20260930.xsd#nwbi_FeesAndCommissionsTrustServicesAndOtherIncome"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_01a0a52a-004c-7161-ad27-0bca86c37e85" xlink:to="loc_nwbi_FeesAndCommissionsTrustServicesAndOtherIncome_01a0a52a-004c-7e9f-990b-58e40d75ca4f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome_01a0c871-f563-7ac9-890c-05c8bff561d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIncome"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_01a0a52a-004c-7161-ad27-0bca86c37e85" xlink:to="loc_us-gaap_OtherIncome_01a0c871-f563-7ac9-890c-05c8bff561d3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_01a0a52a-004c-7bdc-8c2f-69889130f0d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_01a0a52a-004c-7bdc-8c2f-69889130f0d5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_01a0a52a-004c-79aa-92d9-b75312bfb2c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_01a0a52a-004c-79aa-92d9-b75312bfb2c3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_NetInterestAndNoninterestIncome_01a0a52a-004c-7c73-847d-a52d33f06046" xlink:href="nwbi-20260930.xsd#nwbi_NetInterestAndNoninterestIncome"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_nwbi_NetInterestAndNoninterestIncome_01a0a52a-004c-7c73-847d-a52d33f06046" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_01a0a52a-004c-7466-8b51-df9dee8fac3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_01a0a52a-004c-7466-8b51-df9dee8fac3f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_01a0a52a-004c-770d-8400-da38ee76ceed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_01a0a52a-004c-770d-8400-da38ee76ceed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InformationTechnologyAndDataProcessing_01a0a52a-004c-7dfc-92c3-ec25a515668f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InformationTechnologyAndDataProcessing"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_InformationTechnologyAndDataProcessing_01a0a52a-004c-7dfc-92c3-ec25a515668f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OccupancyNet_01a0a52a-004c-7378-8dc0-fd4dfda9895e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OccupancyNet"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_OccupancyNet_01a0a52a-004c-7378-8dc0-fd4dfda9895e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalDepositInsuranceCorporationPremiumExpense_01a0a52a-004c-7698-b6d9-ec4cf57b1d55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FederalDepositInsuranceCorporationPremiumExpense"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_FederalDepositInsuranceCorporationPremiumExpense_01a0a52a-004c-7698-b6d9-ec4cf57b1d55" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_01a0a52a-004c-7794-abcc-c595220bd26b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfessionalFees"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_ProfessionalFees_01a0a52a-004c-7794-abcc-c595220bd26b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_01a0a52a-004c-7b89-b8e4-454ca08ca24e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_01a0a52a-004c-7f99-940f-8179edce7384" xlink:to="loc_us-gaap_LaborAndRelatedExpense_01a0a52a-004c-7b89-b8e4-454ca08ca24e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nwbi_NetInterestAndNoninterestIncome_01a0a52a-004c-7cbd-9033-3844fc6a108a" xlink:href="nwbi-20260930.xsd#nwbi_NetInterestAndNoninterestIncome"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOperating_01a0a52a-004c-7c23-9183-b8a240eb1b61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseOperating"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_NetInterestAndNoninterestIncome_01a0a52a-004c-7cbd-9033-3844fc6a108a" xlink:to="loc_us-gaap_InterestExpenseOperating_01a0a52a-004c-7c23-9183-b8a240eb1b61" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_01a0a52a-004c-7c0d-b9d2-ca27e6253efb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nwbi_NetInterestAndNoninterestIncome_01a0a52a-004c-7cbd-9033-3844fc6a108a" xlink:to="loc_us-gaap_Revenues_01a0a52a-004c-7c0d-b9d2-ca27e6253efb" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
