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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e46c1-c092-7eda-bf04-9a912098995e,g:b19a4597-be15-41c0-ab2e-40ee9d839abd-->
<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:roleRef roleURI="http://www.bxsl.com/role/CondensedConsolidatedStatementsofAssetsandLiabilities" xlink:type="simple" xlink:href="bxsl-20260630.xsd#CondensedConsolidatedStatementsofAssetsandLiabilities"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/CondensedConsolidatedStatementsofAssetsandLiabilities" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" 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_LongTermDebt_019e46c1-e127-798d-b0d0-a86fbfc9e695" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_LongTermDebt_019e46c1-e127-798d-b0d0-a86fbfc9e695" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PayableInvestmentPurchase_019e46c1-e127-75d6-a8e7-94c37ad9f7c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PayableInvestmentPurchase"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_PayableInvestmentPurchase_019e46c1-e127-75d6-a8e7-94c37ad9f7c1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_019e46c1-e127-753a-a9fb-49551f1f234a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_OtherLiabilities_019e46c1-e127-753a-a9fb-49551f1f234a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ManagementFeePayable_019e46c1-e127-7e55-b5b0-a47161a6781d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ManagementFeePayable"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_ManagementFeePayable_019e46c1-e127-7e55-b5b0-a47161a6781d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncentiveFeePayableIncomeBased_019e46c1-e127-7995-8b35-fc8d501b304e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncentiveFeePayableIncomeBased"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_IncentiveFeePayableIncomeBased_019e46c1-e127-7995-8b35-fc8d501b304e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncentiveFeePayableCapitalGainBased_019e46c1-e127-74e1-aa03-4c1e6acf6ad8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncentiveFeePayableCapitalGainBased"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_IncentiveFeePayableCapitalGainBased_019e46c1-e127-74e1-aa03-4c1e6acf6ad8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_019e46c1-e127-797c-9251-09404f5f0cd7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_019e46c1-e127-797c-9251-09404f5f0cd7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e127-7ea6-8a97-16068338ec2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e127-7ea6-8a97-16068338ec2e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionPayable_019e46c1-e127-78c0-9924-1ea9bdd0a2d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DistributionPayable"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_DistributionPayable_019e46c1-e127-78c0-9924-1ea9bdd0a2d9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_TrusteeFeesPayable_019e46c1-e127-7e4d-b471-6ab5c5274aa6" xlink:href="bxsl-20260630.xsd#bxsl_TrusteeFeesPayable"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_bxsl_TrusteeFeesPayable_019e46c1-e127-7e4d-b471-6ab5c5274aa6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_019fa334-efa7-7d8e-b278-eabc495b840b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e46c1-e127-7475-9a51-bda81f742b0e" xlink:to="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_019fa334-efa7-7d8e-b278-eabc495b840b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e46c1-e127-7594-bf4b-7f1583496ddb" 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_StockholdersEquity_019e46c1-e127-711c-b4a0-d547690cdeab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e46c1-e127-7594-bf4b-7f1583496ddb" xlink:to="loc_us-gaap_StockholdersEquity_019e46c1-e127-711c-b4a0-d547690cdeab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019e46c1-e127-774c-ab66-dcb0c116c0d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e46c1-e127-7594-bf4b-7f1583496ddb" xlink:to="loc_us-gaap_Liabilities_019e46c1-e127-774c-ab66-dcb0c116c0d3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019e46c1-e127-7025-a97c-d4671bb27445" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e46c1-e127-7594-bf4b-7f1583496ddb" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019e46c1-e127-7025-a97c-d4671bb27445" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e46c1-e127-73e2-b71b-39b6831081d4" 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_AdditionalPaidInCapital_019e46c1-e127-7904-b78d-8c79217f74f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e46c1-e127-73e2-b71b-39b6831081d4" xlink:to="loc_us-gaap_AdditionalPaidInCapital_019e46c1-e127-7904-b78d-8c79217f74f2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e46c1-e127-7c64-9fd8-7053a9b03894" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e46c1-e127-73e2-b71b-39b6831081d4" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e46c1-e127-7c64-9fd8-7053a9b03894" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019e46c1-e127-79d2-a1bf-d415b03315c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e46c1-e127-73e2-b71b-39b6831081d4" xlink:to="loc_us-gaap_CommonStockValue_019e46c1-e127-79d2-a1bf-d415b03315c5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" 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_ReceivablesFromBrokersDealersAndClearingOrganizations_019e46c1-e127-783a-9dd5-fa04374caf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations_019e46c1-e127-783a-9dd5-fa04374caf3c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e46c1-e127-7f71-9335-1c8464d3df25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e46c1-e127-7f71-9335-1c8464d3df25" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendAndInterestReceivable_019e46c1-e127-72c0-be8c-0a848d0cffaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendAndInterestReceivable"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_DividendAndInterestReceivable_019e46c1-e127-72c0-be8c-0a848d0cffaa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e127-7013-bd3b-011357c85d0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e127-7013-bd3b-011357c85d0e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_019e46c1-e127-7360-9da2-1d837d2d090d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentOwnedAtFairValue"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_019e46c1-e127-7360-9da2-1d837d2d090d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019e46c1-e127-7a5b-b8d9-7cb7c9b2155e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019e46c1-e127-7a5b-b8d9-7cb7c9b2155e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableInvestmentSale_019e46c1-e127-7a1b-85ea-048f1a46034e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivableInvestmentSale"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e46c1-e127-752b-b3f8-9cadbf863a1e" xlink:to="loc_us-gaap_ReceivableInvestmentSale_019e46c1-e127-7a1b-85ea-048f1a46034e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.bxsl.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="bxsl-20260630.xsd#CondensedConsolidatedStatementsofOperations"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e46c1-e127-71c9-ba54-16b4c37d4cd4" 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_InvestmentIncomeOperatingAfterExpenseAndTax_019e46c1-e127-796f-ae25-80f256ed4369" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019e46c1-e127-71c9-ba54-16b4c37d4cd4" xlink:to="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019e46c1-e127-796f-ae25-80f256ed4369" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019e46c1-e127-75c5-9151-4810c65611a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019e46c1-e127-71c9-ba54-16b4c37d4cd4" xlink:to="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019e46c1-e127-75c5-9151-4810c65611a8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-76d4-a934-b8ebba5de40e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GrossInvestmentIncomeOperating"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOperatingPaidInCash_019e46c1-e127-78e0-888b-92a1dc6d0337" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeOperatingPaidInCash"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-76d4-a934-b8ebba5de40e" xlink:to="loc_us-gaap_InterestIncomeOperatingPaidInCash_019e46c1-e127-78e0-888b-92a1dc6d0337" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOperatingPaidInKind_019e46c1-e127-7737-be7e-e1e4a781e843" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeOperatingPaidInKind"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-76d4-a934-b8ebba5de40e" xlink:to="loc_us-gaap_InterestIncomeOperatingPaidInKind_019e46c1-e127-7737-be7e-e1e4a781e843" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendIncomeOperating_019e46c1-e127-736e-8dbe-de4d02bbb0b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendIncomeOperating"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-76d4-a934-b8ebba5de40e" xlink:to="loc_us-gaap_DividendIncomeOperating_019e46c1-e127-736e-8dbe-de4d02bbb0b1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FeeIncome_019e46c1-e127-7c11-b5fa-81b11aa1c6a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FeeIncome"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-76d4-a934-b8ebba5de40e" xlink:to="loc_us-gaap_FeeIncome_019e46c1-e127-7c11-b5fa-81b11aa1c6a7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019e46c1-e127-7ace-9c76-51e45812e036" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncome_019e46c1-e127-73f1-a6a3-22a13c761d31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentIncome"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019e46c1-e127-7ace-9c76-51e45812e036" xlink:to="loc_us-gaap_NetInvestmentIncome_019e46c1-e127-73f1-a6a3-22a13c761d31" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeOperatingTaxExpenseBenefit_019e46c1-e127-7c3e-8d87-7de948d77b0c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeOperatingTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019e46c1-e127-7ace-9c76-51e45812e036" xlink:to="loc_us-gaap_InvestmentIncomeOperatingTaxExpenseBenefit_019e46c1-e127-7c3e-8d87-7de948d77b0c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76cd-8a8f-2ee9f7a1c406" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019e46c1-e127-763b-9d3d-e9553c309671" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndEquitySecuritiesRealizedGainLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76cd-8a8f-2ee9f7a1c406" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019e46c1-e127-763b-9d3d-e9553c309671" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_RealizedGainLossDerivativeOperatingAfterTax_019e46c1-e127-7973-b355-1b1d99ab746c" xlink:href="bxsl-20260630.xsd#bxsl_RealizedGainLossDerivativeOperatingAfterTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76cd-8a8f-2ee9f7a1c406" xlink:to="loc_bxsl_RealizedGainLossDerivativeOperatingAfterTax_019e46c1-e127-7973-b355-1b1d99ab746c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossRealizedAfterTax_019e46c1-e127-7619-8040-b108ae1005b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealizedAfterTax"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76cd-8a8f-2ee9f7a1c406" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossRealizedAfterTax_019e46c1-e127-7619-8040-b108ae1005b3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit_019e46c1-e127-70a2-ae4c-152a176f6916" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76cd-8a8f-2ee9f7a1c406" xlink:to="loc_us-gaap_RealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit_019e46c1-e127-70a2-ae4c-152a176f6916" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeInvestmentExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_019e46c1-e127-7cfa-8150-9b6c25ebf8a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_InterestExpense_019e46c1-e127-7cfa-8150-9b6c25ebf8a0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ManagementFeeExpense_019e46c1-e127-7939-97e1-34f85b164d7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ManagementFeeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_ManagementFeeExpense_019e46c1-e127-7939-97e1-34f85b164d7e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncentiveFeeExpenseIncomeBased_019e46c1-e127-7e86-ac54-4928fcef4545" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncentiveFeeExpenseIncomeBased"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_IncentiveFeeExpenseIncomeBased_019e46c1-e127-7e86-ac54-4928fcef4545" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncentiveFeeExpenseCapitalGainBased_019e46c1-e127-7080-be06-7e96c8297760" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncentiveFeeExpenseCapitalGainBased"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_IncentiveFeeExpenseCapitalGainBased_019e46c1-e127-7080-be06-7e96c8297760" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_019e46c1-e127-7fbf-866d-5f4677b61be0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfessionalFees"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_ProfessionalFees_019e46c1-e127-7fbf-866d-5f4677b61be0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrusteeFees_019e46c1-e127-79b1-b42b-0da018e0d2f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TrusteeFees"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_TrusteeFees_019e46c1-e127-79b1-b42b-0da018e0d2f5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdministrativeFeesExpense_019e46c1-e127-7525-9bd2-3908f22193d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdministrativeFeesExpense"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_AdministrativeFeesExpense_019e46c1-e127-7525-9bd2-3908f22193d5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019e46c1-e127-7fb7-8520-7233f5f87406" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherGeneralAndAdministrativeExpense"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7404-94d7-bd91ffbfcb83" xlink:to="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019e46c1-e127-7fb7-8520-7233f5f87406" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019e46c1-e127-7973-a7f1-c8aedb9c461a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-7a87-915f-2babbd50448b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019e46c1-e127-7973-a7f1-c8aedb9c461a" xlink:to="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-7a87-915f-2babbd50448b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-75d5-ab89-e1333c1afb8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019e46c1-e127-7973-a7f1-c8aedb9c461a" xlink:to="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-75d5-ab89-e1333c1afb8b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncome_019e46c1-e127-71e2-8800-c11bc1dc7166" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentIncome"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7341-8585-a6c8bfef16bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeInvestmentExpense"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetInvestmentIncome_019e46c1-e127-71e2-8800-c11bc1dc7166" xlink:to="loc_us-gaap_InvestmentIncomeInvestmentExpense_019e46c1-e127-7341-8585-a6c8bfef16bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-764b-b050-24522cc471c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GrossInvestmentIncomeOperating"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetInvestmentIncome_019e46c1-e127-71e2-8800-c11bc1dc7166" xlink:to="loc_us-gaap_GrossInvestmentIncomeOperating_019e46c1-e127-764b-b050-24522cc471c1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76e5-86d5-104187075171" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019e46c1-e127-704e-bf7d-a69d1ba7ac75" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76e5-86d5-104187075171" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019e46c1-e127-704e-bf7d-a69d1ba7ac75" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_UnrealizedGainLossDerivativeOperatingAfterTax_019e46c1-e127-7b30-900b-0ae283b37e21" xlink:href="bxsl-20260630.xsd#bxsl_UnrealizedGainLossDerivativeOperatingAfterTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76e5-86d5-104187075171" xlink:to="loc_bxsl_UnrealizedGainLossDerivativeOperatingAfterTax_019e46c1-e127-7b30-900b-0ae283b37e21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealizedAfterTax_019e46c1-e127-71c0-8e95-9bac04db02ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealizedAfterTax"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76e5-86d5-104187075171" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealizedAfterTax_019e46c1-e127-71c0-8e95-9bac04db02ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit_019e46c1-e127-7321-b8f5-6ed784b5822c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019e46c1-e127-76e5-86d5-104187075171" xlink:to="loc_us-gaap_UnrealizedGainLossInvestmentAndDerivativeOperatingTaxExpenseBenefit_019e46c1-e127-7321-b8f5-6ed784b5822c" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.bxsl.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="bxsl-20260630.xsd#CondensedConsolidatedStatementsofCashFlows"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" 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_ProceedsFromIssuanceOfDebt_019e46c1-e128-7249-af3d-de1481f5c7df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfDebt_019e46c1-e128-7249-af3d-de1481f5c7df" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_019e46c1-e128-7aa9-9f09-3a844bb3df23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" xlink:to="loc_us-gaap_RepaymentsOfDebt_019e46c1-e128-7aa9-9f09-3a844bb3df23" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_PaymentsOfDebtIssuanceCostsLineOfCreditArrangements_019e46c1-e128-7eb5-9f1f-6b695cfd2647" xlink:href="bxsl-20260630.xsd#bxsl_PaymentsOfDebtIssuanceCostsLineOfCreditArrangements"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" xlink:to="loc_bxsl_PaymentsOfDebtIssuanceCostsLineOfCreditArrangements_019e46c1-e128-7eb5-9f1f-6b695cfd2647" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019e46c1-e128-7056-8a16-acdeceeffb10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019e46c1-e128-7056-8a16-acdeceeffb10" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_019e46c1-e128-7446-96ea-f1a531a60d20" 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="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" xlink:to="loc_us-gaap_PaymentsOfDividends_019e46c1-e128-7446-96ea-f1a531a60d20" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019e46c1-e128-7ca8-a7f3-6daa26c6c0ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-73cb-83d1-8e4e9e3c227f" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019e46c1-e128-7ca8-a7f3-6daa26c6c0ae" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019e46c1-e128-7313-b32b-f693af34b638" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7395-b06b-69ca6694a944" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019e46c1-e128-7313-b32b-f693af34b638" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7395-b06b-69ca6694a944" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-700a-afbe-cc004a20cb2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_019e46c1-e128-7313-b32b-f693af34b638" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e46c1-e128-700a-afbe-cc004a20cb2f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" 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_019e46c1-e128-7bd6-99ed-9ae7aa22b351" 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="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_NetIncomeLoss_019e46c1-e128-7bd6-99ed-9ae7aa22b351" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019e46c1-e128-7edd-904e-446f80d7ca92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019e46c1-e128-7edd-904e-446f80d7ca92" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_019e46c1-e128-70d7-848d-5b7557e97f2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_019e46c1-e128-70d7-848d-5b7557e97f2e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_019e46c1-e128-7ed1-97a1-8dabd0ccd550" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_019e46c1-e128-7ed1-97a1-8dabd0ccd550" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019e46c1-e128-7f86-8e8c-231ea777862e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndEquitySecuritiesRealizedGainLoss"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019e46c1-e128-7f86-8e8c-231ea777862e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss_019e46c1-e128-75cb-b2a2-98b321dab04f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss_019e46c1-e128-75cb-b2a2-98b321dab04f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_019e46c1-e128-714d-94b3-b2b1397f80f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_019e46c1-e128-714d-94b3-b2b1397f80f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_PaidInKindInterestNoncash_019e46c1-e128-7936-9e91-b2230fdf3fea" xlink:href="bxsl-20260630.xsd#bxsl_PaidInKindInterestNoncash"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_bxsl_PaidInKindInterestNoncash_019e46c1-e128-7936-9e91-b2230fdf3fea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_AmortizationOfDebtIssuanceCostsLineOfCreditArrangements_019e46c1-e128-7e33-a8f6-03fba4b90705" xlink:href="bxsl-20260630.xsd#bxsl_AmortizationOfDebtIssuanceCostsLineOfCreditArrangements"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_bxsl_AmortizationOfDebtIssuanceCostsLineOfCreditArrangements_019e46c1-e128-7e33-a8f6-03fba4b90705" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_019e46c1-e128-7196-b7a3-ae9677daa29b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_019e46c1-e128-7196-b7a3-ae9677daa29b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity_019e46c1-e128-7597-ab6f-12483312c0a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity_019e46c1-e128-7597-ab6f-12483312c0a6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDispositionOfInvestmentOperatingActivity_019e46c1-e128-7d55-97d6-41dee21d6d91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromDispositionOfInvestmentOperatingActivity"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_ProceedsFromDispositionOfInvestmentOperatingActivity_019e46c1-e128-7d55-97d6-41dee21d6d91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable_019e46c1-e128-78fa-bd58-7ab89d9ce9de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable"/>
    <link:calculationArc order="13" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable_019e46c1-e128-78fa-bd58-7ab89d9ce9de" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivableForInvestmentSold_019e46c1-e128-7114-82c2-0ed7db53844e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInReceivableForInvestmentSold"/>
    <link:calculationArc order="14" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivableForInvestmentSold_019e46c1-e128-7114-82c2-0ed7db53844e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDerivativeAssets_019e46c1-e128-7ca6-aef5-6375e0ab1c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInDerivativeAssets"/>
    <link:calculationArc order="15" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInDerivativeAssets_019e46c1-e128-7ca6-aef5-6375e0ab1c7e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInBrokerageReceivables_019e46c1-e128-75fe-a0c9-9d0e0ab4c095" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInBrokerageReceivables"/>
    <link:calculationArc order="16" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInBrokerageReceivables_019e46c1-e128-75fe-a0c9-9d0e0ab4c095" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPayableForInvestmentPurchased_019e46c1-e128-7564-a0d5-1e4f8d583435" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInPayableForInvestmentPurchased"/>
    <link:calculationArc order="17" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInPayableForInvestmentPurchased_019e46c1-e128-7564-a0d5-1e4f8d583435" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDueToAffiliates_019e46c1-e128-7d30-bc2c-ca4781934883" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInDueToAffiliates"/>
    <link:calculationArc order="18" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInDueToAffiliates_019e46c1-e128-7d30-bc2c-ca4781934883" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInManagementFeePayable_019e46c1-e128-773c-80d9-c7ac3a5f6442" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInManagementFeePayable"/>
    <link:calculationArc order="19" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInManagementFeePayable_019e46c1-e128-773c-80d9-c7ac3a5f6442" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncentiveFeePayableIncomeBased_019e46c1-e128-7940-89ba-afd2e0c9d970" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInIncentiveFeePayableIncomeBased"/>
    <link:calculationArc order="20" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInIncentiveFeePayableIncomeBased_019e46c1-e128-7940-89ba-afd2e0c9d970" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncentiveFeePayableCapitalGainBased_019e46c1-e128-7294-8ebc-2a54aab52dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInIncentiveFeePayableCapitalGainBased"/>
    <link:calculationArc order="21" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInIncentiveFeePayableCapitalGainBased_019e46c1-e128-7294-8ebc-2a54aab52dd1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_019e46c1-e128-711e-96d1-1f0ce76d73ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInInterestPayableNet"/>
    <link:calculationArc order="22" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_019e46c1-e128-711e-96d1-1f0ce76d73ad" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities_019e46c1-e128-7d4c-9170-31d763bff34d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities"/>
    <link:calculationArc order="23" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities_019e46c1-e128-7d4c-9170-31d763bff34d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_019e46c1-e128-775b-82df-5d1569f5fdd7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized"/>
    <link:calculationArc order="24" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e46c1-e128-7b71-8d07-797034717a4b" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_019e46c1-e128-775b-82df-5d1569f5fdd7" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.bxsl.com/role/DerivativesOffsettingDerivativeInstrumentDetails" xlink:type="simple" xlink:href="bxsl-20260630.xsd#DerivativesOffsettingDerivativeInstrumentDetails"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/DerivativesOffsettingDerivativeInstrumentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-7166-8bf9-f85e750b9d94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e46c1-e128-7831-a3b0-7ab375fa6724" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-7166-8bf9-f85e750b9d94" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e46c1-e128-7831-a3b0-7ab375fa6724" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset_019e46c1-e128-77f8-8476-c99f56b9aa0f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-7166-8bf9-f85e750b9d94" xlink:to="loc_us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset_019e46c1-e128-77f8-8476-c99f56b9aa0f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e46c1-e128-7a63-ad5e-e55bf081442c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-7166-8bf9-f85e750b9d94" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e46c1-e128-7a63-ad5e-e55bf081442c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-79f5-828b-eb4bfc47dd9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_019e46c1-e128-72fa-a22e-987c94069fee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-79f5-828b-eb4bfc47dd9b" xlink:to="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_019e46c1-e128-72fa-a22e-987c94069fee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e46c1-e128-7eb2-838e-2d832a6a3ee3" 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="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-79f5-828b-eb4bfc47dd9b" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e46c1-e128-7eb2-838e-2d832a6a3ee3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e46c1-e128-70e7-9ee5-5064ab731655" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeLiabilityAfterOffsetSubjectToMasterNettingArrangement_019e46c1-e128-79f5-828b-eb4bfc47dd9b" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e46c1-e128-70e7-9ee5-5064ab731655" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.bxsl.com/role/BorrowingsContractualMaturitiesOfOutstandingPrincipalDetails" xlink:type="simple" xlink:href="bxsl-20260630.xsd#BorrowingsContractualMaturitiesOfOutstandingPrincipalDetails"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/BorrowingsContractualMaturitiesOfOutstandingPrincipalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_DebtLongTermAndShortTermCombinedAmountGross_019e46c1-e1f7-7256-81cb-34b3ca563398" xlink:href="bxsl-20260630.xsd#bxsl_DebtLongTermAndShortTermCombinedAmountGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingLessThanOneYear_019e46c1-e1f7-7559-a032-ad7237d180f5" xlink:href="bxsl-20260630.xsd#bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingLessThanOneYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_bxsl_DebtLongTermAndShortTermCombinedAmountGross_019e46c1-e1f7-7256-81cb-34b3ca563398" xlink:to="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingLessThanOneYear_019e46c1-e1f7-7559-a032-ad7237d180f5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearOneThroughThree_019e46c1-e1f7-736d-abd4-eceaf6550cd0" xlink:href="bxsl-20260630.xsd#bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearOneThroughThree"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_bxsl_DebtLongTermAndShortTermCombinedAmountGross_019e46c1-e1f7-7256-81cb-34b3ca563398" xlink:to="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearOneThroughThree_019e46c1-e1f7-736d-abd4-eceaf6550cd0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearThreeThroughFive_019e46c1-e1f7-764b-b319-584b562f595d" xlink:href="bxsl-20260630.xsd#bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearThreeThroughFive"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_bxsl_DebtLongTermAndShortTermCombinedAmountGross_019e46c1-e1f7-7256-81cb-34b3ca563398" xlink:to="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearThreeThroughFive_019e46c1-e1f7-764b-b319-584b562f595d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearAfterFive_019e46c1-e1f7-7621-9bfe-2b8b25deefe3" xlink:href="bxsl-20260630.xsd#bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearAfterFive"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_bxsl_DebtLongTermAndShortTermCombinedAmountGross_019e46c1-e1f7-7256-81cb-34b3ca563398" xlink:to="loc_bxsl_DebtLongTermAndShortTermMaturitiesRepaymentsOfPrincipalInRollingYearAfterFive_019e46c1-e1f7-7621-9bfe-2b8b25deefe3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.bxsl.com/role/BorrowingsInterestExpenseDetails" xlink:type="simple" xlink:href="bxsl-20260630.xsd#BorrowingsInterestExpenseDetails"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/BorrowingsInterestExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1_019e46c1-e1f7-74df-858c-02ae070313b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:to="loc_us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1_019e46c1-e1f7-74df-858c-02ae070313b7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseBorrowings_019e46c1-e1f7-7701-bcbe-3514776c6e9a" 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="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:to="loc_us-gaap_InterestExpenseBorrowings_019e46c1-e1f7-7701-bcbe-3514776c6e9a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019e46c1-e1f7-72fe-a989-a18bb94dcaee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019e46c1-e1f7-72fe-a989-a18bb94dcaee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1_019e46c1-e1f7-7ed2-9a8d-f6eef44ee655" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:to="loc_us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1_019e46c1-e1f7-7ed2-9a8d-f6eef44ee655" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_bxsl_AmortizationOfDebtIssuanceCostsLineOfCreditArrangements_019e46c1-e1f7-7525-a550-8112930e2c0b" xlink:href="bxsl-20260630.xsd#bxsl_AmortizationOfDebtIssuanceCostsLineOfCreditArrangements"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:to="loc_bxsl_AmortizationOfDebtIssuanceCostsLineOfCreditArrangements_019e46c1-e1f7-7525-a550-8112930e2c0b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityFee_019e46c1-e1f7-7db2-b271-c89eaab5b9f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityFee"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_019e46c1-e1f7-7977-b8d8-516b434140f0" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityFee_019e46c1-e1f7-7db2-b271-c89eaab5b9f0" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.bxsl.com/role/FinancialHighlightsandSeniorSecuritiesDetails" xlink:type="simple" xlink:href="bxsl-20260630.xsd#FinancialHighlightsandSeniorSecuritiesDetails"/>
  <link:calculationLink xlink:role="http://www.bxsl.com/role/FinancialHighlightsandSeniorSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease_019e46c1-e1f7-7801-9db1-5d7bf74de7d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyTaxReturnOfCapitalDistributionPerShare_019e46c1-e1f7-71ea-b3f4-fe5fb2e3029f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyTaxReturnOfCapitalDistributionPerShare"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease_019e46c1-e1f7-7801-9db1-5d7bf74de7d5" xlink:to="loc_us-gaap_InvestmentCompanyTaxReturnOfCapitalDistributionPerShare_019e46c1-e1f7-71ea-b3f4-fe5fb2e3029f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare_019e46c1-e1f7-7dab-8c6b-7699ee8f06cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease_019e46c1-e1f7-7801-9db1-5d7bf74de7d5" xlink:to="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare_019e46c1-e1f7-7dab-8c6b-7699ee8f06cb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyDistributionToShareholdersPerShare_019e46c1-e1f7-77e9-984d-f63f3573fe2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyDistributionToShareholdersPerShare"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease_019e46c1-e1f7-7801-9db1-5d7bf74de7d5" xlink:to="loc_us-gaap_InvestmentCompanyDistributionToShareholdersPerShare_019e46c1-e1f7-77e9-984d-f63f3573fe2d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare_019e46c1-e1f7-7e73-b8e0-840f2c0d5629" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare_019e46c1-e1f7-7131-9338-9924924c07d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare_019e46c1-e1f7-7e73-b8e0-840f2c0d5629" xlink:to="loc_us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare_019e46c1-e1f7-7131-9338-9924924c07d4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare_019e46c1-e1f7-7d21-9434-40b778fa617d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare_019e46c1-e1f7-7e73-b8e0-840f2c0d5629" xlink:to="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare_019e46c1-e1f7-7d21-9434-40b778fa617d" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
