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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019d1bac-b918-7460-844b-4286f2847287,g:19806af6-486c-4542-bb2f-6d1b07e280a8-->
<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://fskkrcapitalcorp.com/role/ConsolidatedBalanceSheets" xlink:type="simple" xlink:href="fsk-20260331.xsd#ConsolidatedBalanceSheets"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/ConsolidatedBalanceSheets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019d1bac-cb47-7182-8e0e-0dd1943115fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019d1bac-cb47-791c-b104-c8b1cfb3a262" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-7182-8e0e-0dd1943115fc" xlink:to="loc_us-gaap_StockholdersEquity_019d1bac-cb47-791c-b104-c8b1cfb3a262" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019d1bac-cb47-7538-bee8-6093c8f4bead" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019d1bac-cb47-7182-8e0e-0dd1943115fc" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019d1bac-cb47-7538-bee8-6093c8f4bead" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019d1bac-cb47-76ac-a232-ec3889b366d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019d1bac-cb47-7182-8e0e-0dd1943115fc" xlink:to="loc_us-gaap_Liabilities_019d1bac-cb47-76ac-a232-ec3889b366d1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019d1bac-cb47-7cbe-8857-a640c48c024e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_019d1bac-cb47-7cbe-8857-a640c48c024e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssets_019d1bac-cb47-77ba-9307-b018f33f61fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssets"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssets_019d1bac-cb47-77ba-9307-b018f33f61fb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendAndInterestReceivable_019d1bac-cb47-7ee8-9aff-31ee9e337336" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_DividendAndInterestReceivable_019d1bac-cb47-7ee8-9aff-31ee9e337336" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableInvestmentSale_019d1bac-cb47-7e61-b54c-98f814aeacb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReceivableInvestmentSale"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_ReceivableInvestmentSale_019d1bac-cb47-7e61-b54c-98f814aeacb0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019d1bac-cb47-73cb-a8b9-7cbef5dbc91b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019d1bac-cb47-73cb-a8b9-7cbef5dbc91b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashHeldInForeignCurrency_019d1bac-cb47-7d7c-9f87-cfe8c22e9731" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashHeldInForeignCurrency"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_CashHeldInForeignCurrency_019d1bac-cb47-7d7c-9f87-cfe8c22e9731" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_019d1bac-cb47-7144-ba94-941fb785a571" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentOwnedAtFairValue"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_019d1bac-cb47-7144-ba94-941fb785a571" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashNotHeldInForeignCurrency_019d1bac-cb47-74a1-b6b9-b6a6085e1246" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashNotHeldInForeignCurrency"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_CashNotHeldInForeignCurrency_019d1bac-cb47-74a1-b6b9-b6a6085e1246" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_019df2a8-bdaf-7528-af6e-0b58525eafe5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCash"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb47-7986-a5f7-81a457fea2da" xlink:to="loc_us-gaap_RestrictedCash_019df2a8-bdaf-7528-af6e-0b58525eafe5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedProfessionalFeesCurrentAndNoncurrent_019d1bac-cb47-7be3-90b8-d59a31194231" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedProfessionalFeesCurrentAndNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_AccruedProfessionalFeesCurrentAndNoncurrent_019d1bac-cb47-7be3-90b8-d59a31194231" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ManagementFeePayable_019d1bac-cb47-708d-bf21-7c46d3bf4cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ManagementFeePayable"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_ManagementFeePayable_019d1bac-cb47-708d-bf21-7c46d3bf4cfe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionPayable_019d1bac-cb47-7d1b-bd01-7599c3b1d8bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DistributionPayable"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_DistributionPayable_019d1bac-cb47-7d1b-bd01-7599c3b1d8bb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019d1bac-cb47-7fda-8c35-44b68142779f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_LongTermDebt_019d1bac-cb47-7fda-8c35-44b68142779f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrentAndNoncurrent_019d1bac-cb47-7efa-a177-b0d62d12d917" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_InterestPayableCurrentAndNoncurrent_019d1bac-cb47-7efa-a177-b0d62d12d917" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncentiveFeePayable_019d1bac-cb47-728b-b306-567f1b2bf972" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncentiveFeePayable"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_IncentiveFeePayable_019d1bac-cb47-728b-b306-567f1b2bf972" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrentAndNoncurrent_019d1bac-cb47-70ce-ab0a-adce2da19a32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAccruedLiabilitiesCurrentAndNoncurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrentAndNoncurrent_019d1bac-cb47-70ce-ab0a-adce2da19a32" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PayableInvestmentPurchase_019d1bac-cb47-70b5-aa20-a28d31e09a86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PayableInvestmentPurchase"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_PayableInvestmentPurchase_019d1bac-cb47-70b5-aa20-a28d31e09a86" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019d1bac-cb47-746b-9bcd-3db9fabc311b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb47-72c8-a915-8e1f137f4b0c" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019d1bac-cb47-746b-9bcd-3db9fabc311b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019d1bac-cb47-7a6e-997f-14125b099a75" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_019d1bac-cb47-78e3-9ef5-b001aeb4ded6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019d1bac-cb47-7a6e-997f-14125b099a75" xlink:to="loc_us-gaap_PreferredStockValue_019d1bac-cb47-78e3-9ef5-b001aeb4ded6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_019d1bac-cb47-7000-b7c5-d4e4cbcbece8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019d1bac-cb47-7a6e-997f-14125b099a75" xlink:to="loc_us-gaap_AdditionalPaidInCapital_019d1bac-cb47-7000-b7c5-d4e4cbcbece8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019d1bac-cb47-7974-ac3d-7ac125092dae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-7a6e-997f-14125b099a75" xlink:to="loc_us-gaap_CommonStockValue_019d1bac-cb47-7974-ac3d-7ac125092dae" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019d1bac-cb47-7ee9-8697-53317abec076" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019d1bac-cb47-7a6e-997f-14125b099a75" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019d1bac-cb47-7ee9-8697-53317abec076" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="fsk-20260331.xsd#UnauditedConsolidatedStatementsofOperations"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedStatementsofOperations" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInvestmentExpense_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInvestmentExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019d1bac-cb47-7e63-bf53-a9b783ad6861" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherGeneralAndAdministrativeExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:to="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019d1bac-cb47-7e63-bf53-a9b783ad6861" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ManagementFeeExpense_019d1bac-cb47-798a-b58e-95746fc47593" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:to="loc_us-gaap_ManagementFeeExpense_019d1bac-cb47-798a-b58e-95746fc47593" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_019d1bac-cb47-7626-a16a-6b8f1df2c1e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfessionalFees"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:to="loc_us-gaap_ProfessionalFees_019d1bac-cb47-7626-a16a-6b8f1df2c1e7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOperating_019d1bac-cb47-77d2-aa01-e104963c2311" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseOperating"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:to="loc_us-gaap_InterestExpenseOperating_019d1bac-cb47-77d2-aa01-e104963c2311" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdministrativeFeesExpense_019d1bac-cb47-74db-806c-af7e62ae8157" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdministrativeFeesExpense"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:to="loc_us-gaap_AdministrativeFeesExpense_019d1bac-cb47-74db-806c-af7e62ae8157" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncentiveFeeExpense_019d1bac-cb47-7e82-9353-838656b8ad06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncentiveFeeExpense"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeInvestmentExpense_019d1bac-cb47-7e56-b7d8-6c6caaa7cf00" xlink:to="loc_us-gaap_IncentiveFeeExpense_019d1bac-cb47-7e82-9353-838656b8ad06" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7df9-96c5-7633253ddc4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7a11-b84e-57f2ce87c3ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-7df9-96c5-7633253ddc4a" xlink:to="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7a11-b84e-57f2ce87c3ad" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7291-9c1a-d5da593407de" xlink:href="fsk-20260331.xsd#fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7df9-96c5-7633253ddc4a" xlink:to="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7291-9c1a-d5da593407de" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:href="fsk-20260331.xsd#fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019d1bac-cb47-71ec-9556-ff649c8395c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtAndEquitySecuritiesRealizedGainLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019d1bac-cb47-71ec-9556-ff649c8395c4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_019d1bac-cb47-7763-a4bd-77b2137c99ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_019d1bac-cb47-7763-a4bd-77b2137c99ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfDerivatives_019d1bac-cb47-7a1b-94d1-22418be14315" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfDerivatives"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:to="loc_us-gaap_GainLossOnSaleOfDerivatives_019d1bac-cb47-7a1b-94d1-22418be14315" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_019d1bac-cb47-70b9-a3d7-e4f0cbd67d48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_019d1bac-cb47-70b9-a3d7-e4f0cbd67d48" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019d1bac-cb47-7450-b9db-8bd0715bd968" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019d1bac-cb47-7450-b9db-8bd0715bd968" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_019d1bac-cb47-7ad5-ac5e-8a5ffb7c6a85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionBeforeTax_019d1bac-cb47-7cb8-a0e5-e179ddf0466e" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_019d1bac-cb47-7ad5-ac5e-8a5ffb7c6a85" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7936-9c1c-5ce8a9e46eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossInvestmentIncomeOperating_019daab8-8b90-7ce6-8639-609a64fa10fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossInvestmentIncomeOperating"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7936-9c1c-5ce8a9e46eb7" xlink:to="loc_us-gaap_GrossInvestmentIncomeOperating_019daab8-8b90-7ce6-8639-609a64fa10fa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInvestmentExpense_019daab8-bfd7-7b25-acdf-9a78f449d6ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInvestmentExpense"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7936-9c1c-5ce8a9e46eb7" xlink:to="loc_us-gaap_InvestmentIncomeInvestmentExpense_019daab8-bfd7-7b25-acdf-9a78f449d6ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossInvestmentIncomeOperating_019d1bac-cb47-797d-bd19-d26aaeb869b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossInvestmentIncomeOperating"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FeeIncome_019d1bac-cb47-7cc1-b812-74e5b277459d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FeeIncome"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019d1bac-cb47-797d-bd19-d26aaeb869b2" xlink:to="loc_us-gaap_FeeIncome_019d1bac-cb47-7cc1-b812-74e5b277459d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOperatingPaidInCash_019d1bac-cb47-77f6-8273-ec88681b282a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeOperatingPaidInCash"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019d1bac-cb47-797d-bd19-d26aaeb869b2" xlink:to="loc_us-gaap_InterestIncomeOperatingPaidInCash_019d1bac-cb47-77f6-8273-ec88681b282a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOperatingPaidInKind_019d1bac-cb47-73cf-b796-c15192c3b2a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeOperatingPaidInKind"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019d1bac-cb47-797d-bd19-d26aaeb869b2" xlink:to="loc_us-gaap_InterestIncomeOperatingPaidInKind_019d1bac-cb47-73cf-b796-c15192c3b2a6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendIncomeOperating_019d1bac-cb47-7bed-bbaa-18d218129904" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendIncomeOperating"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossInvestmentIncomeOperating_019d1bac-cb47-797d-bd19-d26aaeb869b2" xlink:to="loc_us-gaap_DividendIncomeOperating_019d1bac-cb47-7bed-bbaa-18d218129904" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedStatementsofChangesinNetAssets" xlink:type="simple" xlink:href="fsk-20260331.xsd#UnauditedConsolidatedStatementsofChangesinNetAssets"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedStatementsofChangesinNetAssets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDividendDistributionIncreaseDecrease_019d1bac-cb47-7311-b068-853d09f1c7c0" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDividendDistributionIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7e76-9225-5c0e61dc550c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyDividendDistribution"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_InvestmentCompanyDividendDistributionIncreaseDecrease_019d1bac-cb47-7311-b068-853d09f1c7c0" xlink:to="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7e76-9225-5c0e61dc550c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease_019d1bac-cb47-7e93-b6d4-fae6d44750d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityPeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDividendDistributionIncreaseDecrease_019d1bac-cb47-71b3-a695-367b8dc49edc" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDividendDistributionIncreaseDecrease"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease_019d1bac-cb47-7e93-b6d4-fae6d44750d9" xlink:to="loc_fsk_InvestmentCompanyDividendDistributionIncreaseDecrease_019d1bac-cb47-71b3-a695-367b8dc49edc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyIncreaseDecreaseFromShareTransaction_019d1bac-cb47-7bc0-bdc3-af605a6fbc6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyIncreaseDecreaseFromShareTransaction"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease_019d1bac-cb47-7e93-b6d4-fae6d44750d9" xlink:to="loc_us-gaap_InvestmentCompanyIncreaseDecreaseFromShareTransaction_019d1bac-cb47-7bc0-bdc3-af605a6fbc6c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7854-a90d-201b23e44529" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease_019d1bac-cb47-7e93-b6d4-fae6d44750d9" xlink:to="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7854-a90d-201b23e44529" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyIncreaseDecreaseFromShareTransaction_019d1bac-cb47-734d-b528-ba51890303b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyIncreaseDecreaseFromShareTransaction"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_019d1bac-cb47-737e-9e1f-4f88f9404adb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyIncreaseDecreaseFromShareTransaction_019d1bac-cb47-734d-b528-ba51890303b5" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_019d1bac-cb47-737e-9e1f-4f88f9404adb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7f96-930e-e0802f1d314a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019d1bac-cb47-7ad4-a910-1b93a55edfa7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7f96-930e-e0802f1d314a" xlink:to="loc_us-gaap_RealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionPriceChangeOperatingAfterTax_019d1bac-cb47-7ad4-a910-1b93a55edfa7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7ef2-a940-0496941a975f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7f96-930e-e0802f1d314a" xlink:to="loc_us-gaap_InvestmentIncomeOperatingAfterExpenseAndTax_019d1bac-cb47-7ef2-a940-0496941a975f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_019d1bac-cb47-7164-89fb-b925523c61ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7f96-930e-e0802f1d314a" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_019d1bac-cb47-7164-89fb-b925523c61ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossInvestmentAndDerivativeOperatingAfterTax_019d1bac-cb47-767a-9632-5a4c0b3a3cea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrealizedGainLossInvestmentAndDerivativeOperatingAfterTax"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7f96-930e-e0802f1d314a" xlink:to="loc_us-gaap_UnrealizedGainLossInvestmentAndDerivativeOperatingAfterTax_019d1bac-cb47-767a-9632-5a4c0b3a3cea" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="fsk-20260331.xsd#UnauditedConsolidatedStatementsofCashFlows"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7c68-b7ce-70335662d246" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_NetIncomeLoss_019d1bac-cb47-7c68-b7ce-70335662d246" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity_019d1bac-cb47-7f2f-8b26-c34221c4a21e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity_019d1bac-cb47-7f2f-8b26-c34221c4a21e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOperatingPaidInKind_019d1bac-cb47-7288-ad19-9ad5e49dd1b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeOperatingPaidInKind"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_InterestIncomeOperatingPaidInKind_019d1bac-cb47-7288-ad19-9ad5e49dd1b8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDispositionOfInvestmentOperatingActivity_019d1bac-cb47-7edf-a7be-4723c5ef1210" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromDispositionOfInvestmentOperatingActivity"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_ProceedsFromDispositionOfInvestmentOperatingActivity_019d1bac-cb47-7edf-a7be-4723c5ef1210" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019d1bac-cb47-730e-996b-917a07caa927" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesRealizedGainLoss_019d1bac-cb47-730e-996b-917a07caa927" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019d1bac-cb47-7e38-a3a6-b27f02a653ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_DebtAndEquitySecuritiesUnrealizedGainLoss_019d1bac-cb47-7e38-a3a6-b27f02a653ea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_UnrealizedGainLossOnDerivativesIncludingEffectsFromMerger_019d1bac-cb47-7714-bd49-39a5ddb5931c" xlink:href="fsk-20260331.xsd#fsk_UnrealizedGainLossOnDerivativesIncludingEffectsFromMerger"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_fsk_UnrealizedGainLossOnDerivativesIncludingEffectsFromMerger_019d1bac-cb47-7714-bd49-39a5ddb5931c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_019d1bac-cb47-7a14-84be-7eb2ef2ed666" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_019d1bac-cb47-7a14-84be-7eb2ef2ed666" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019d1bac-cb47-74f1-a147-92a28909eb1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019d1bac-cb47-74f1-a147-92a28909eb1d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_ForeignCurrencyTransactionGainLossUnrealizedGainLossOnBorrowings_019d1bac-cb47-730e-95f3-cec2b0ce0ebd" xlink:href="fsk-20260331.xsd#fsk_ForeignCurrencyTransactionGainLossUnrealizedGainLossOnBorrowings"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_fsk_ForeignCurrencyTransactionGainLossUnrealizedGainLossOnBorrowings_019d1bac-cb47-730e-95f3-cec2b0ce0ebd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivableForInvestmentSold_019d1bac-cb47-73b2-91cb-6b953f32849e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInReceivableForInvestmentSold"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivableForInvestmentSold_019d1bac-cb47-73b2-91cb-6b953f32849e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable_019d1bac-cb47-75c0-971a-5f53e5cebd9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable"/>
    <link:calculationArc order="12" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable_019d1bac-cb47-75c0-971a-5f53e5cebd9a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019d1bac-cb47-722c-9265-435656b5c985" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="13" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019d1bac-cb47-722c-9265-435656b5c985" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPayableForInvestmentPurchased_019d1bac-cb47-7f0b-b6f2-31c385dbcad8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPayableForInvestmentPurchased"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInPayableForInvestmentPurchased_019d1bac-cb47-7f0b-b6f2-31c385dbcad8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInManagementFeePayable_019d1bac-cb47-7a20-b44c-7628f1d466c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInManagementFeePayable"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInManagementFeePayable_019d1bac-cb47-7a20-b44c-7628f1d466c6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncentiveFeePayable_019d1bac-cb47-7881-acab-7f1b01faff35" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInIncentiveFeePayable"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInIncentiveFeePayable_019d1bac-cb47-7881-acab-7f1b01faff35" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_IncreaseDecreaseInAccruedProfessionalFees_019d1bac-cb47-77df-a4b5-8aa9e80a69f0" xlink:href="fsk-20260331.xsd#fsk_IncreaseDecreaseInAccruedProfessionalFees"/>
    <link:calculationArc order="17" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_fsk_IncreaseDecreaseInAccruedProfessionalFees_019d1bac-cb47-77df-a4b5-8aa9e80a69f0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_019d1bac-cb47-78de-9920-2f27e78614fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInterestPayableNet"/>
    <link:calculationArc order="18" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInInterestPayableNet_019d1bac-cb47-78de-9920-2f27e78614fa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherAccruedLiabilities_019d1bac-cb47-7245-a88a-d702799a6530" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherAccruedLiabilities"/>
    <link:calculationArc order="19" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-75fb-95fd-281bc13a038c" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherAccruedLiabilities_019d1bac-cb47-7245-a88a-d702799a6530" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-71d1-9d0e-64caca66ca67" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_019d1bac-cb47-7a81-9f46-b564ce7395ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-71d1-9d0e-64caca66ca67" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_019d1bac-cb47-7a81-9f46-b564ce7395ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019d1bac-cb47-737d-b17f-b225ef34e13b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-71d1-9d0e-64caca66ca67" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_019d1bac-cb47-737d-b17f-b225ef34e13b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019d1bac-cb47-7de8-80ae-7250230e5413" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-71d1-9d0e-64caca66ca67" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019d1bac-cb47-7de8-80ae-7250230e5413" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_019d1bac-cb47-7c89-9c1c-84ef7c399687" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-71d1-9d0e-64caca66ca67" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_019d1bac-cb47-7c89-9c1c-84ef7c399687" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019d1bac-cb47-707c-9cf4-79bd9f87964e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-7fe6-9312-e4e6809024bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019d1bac-cb47-707c-9cf4-79bd9f87964e" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019d1bac-cb47-7fe6-9312-e4e6809024bf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-7775-880b-690e726bfce0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019d1bac-cb47-707c-9cf4-79bd9f87964e" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019d1bac-cb47-7775-880b-690e726bfce0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019df362-577d-766f-b6dd-e02e9b095928" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019d1bac-cb47-707c-9cf4-79bd9f87964e" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019df362-577d-766f-b6dd-e02e9b095928" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedScheduleofInvestments" xlink:type="simple" xlink:href="fsk-20260331.xsd#UnauditedConsolidatedScheduleofInvestments"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/UnauditedConsolidatedScheduleofInvestments" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNet_019d1bac-cb47-7b93-a2d8-0f7596928bda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_019d1bac-cb47-781d-9efa-88756deef239" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentOwnedAtFairValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsNet_019d1bac-cb47-7b93-a2d8-0f7596928bda" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_019d1bac-cb47-781d-9efa-88756deef239" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonInvestmentAssetsLessNonInvestmentLiabilities_019d1bac-cb47-7251-bdb6-e5dfd15c1681" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonInvestmentAssetsLessNonInvestmentLiabilities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsNet_019d1bac-cb47-7b93-a2d8-0f7596928bda" xlink:to="loc_us-gaap_NonInvestmentAssetsLessNonInvestmentLiabilities_019d1bac-cb47-7251-bdb6-e5dfd15c1681" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/ShareTransactionsScheduleofCommonStockTransactionsDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#ShareTransactionsScheduleofCommonStockTransactionsDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/ShareTransactionsScheduleofCommonStockTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease_019d1bac-cb47-7713-a072-30f87a82c0bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_019d1bac-cb47-7a1e-9abb-2c76de5772da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease_019d1bac-cb47-7713-a072-30f87a82c0bf" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_019d1bac-cb47-7a1e-9abb-2c76de5772da" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_NetStockIssuedRepurchaseValue_019d1bac-cb47-7660-885b-ba241c96c42d" xlink:href="fsk-20260331.xsd#fsk_NetStockIssuedRepurchaseValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019d1bac-cb47-791e-b370-fd830c0e857b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_NetStockIssuedRepurchaseValue_019d1bac-cb47-7660-885b-ba241c96c42d" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019d1bac-cb47-791e-b370-fd830c0e857b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/DistributionsScheduleofCashDistributionsDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#DistributionsScheduleofCashDistributionsDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/DistributionsScheduleofCashDistributionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_019d1bac-cb47-755a-88fc-00a8c0e6a804" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_CommonStockDividendsPerShareDeclaredSupplemental_019d1bac-cb47-72d4-93ad-39a9d30438d8" xlink:href="fsk-20260331.xsd#fsk_CommonStockDividendsPerShareDeclaredSupplemental"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CommonStockDividendsPerShareDeclared_019d1bac-cb47-755a-88fc-00a8c0e6a804" xlink:to="loc_fsk_CommonStockDividendsPerShareDeclaredSupplemental_019d1bac-cb47-72d4-93ad-39a9d30438d8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_CommonStockDividendsPerShareDeclaredOrdinary_019d1bac-cb47-7b6d-86f4-cc4657153526" xlink:href="fsk-20260331.xsd#fsk_CommonStockDividendsPerShareDeclaredOrdinary"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CommonStockDividendsPerShareDeclared_019d1bac-cb47-755a-88fc-00a8c0e6a804" xlink:to="loc_fsk_CommonStockDividendsPerShareDeclaredOrdinary_019d1bac-cb47-7b6d-86f4-cc4657153526" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/DistributionsScheduleofCashDistributionsonCommonStockDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#DistributionsScheduleofCashDistributionsonCommonStockDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/DistributionsScheduleofCashDistributionsonCommonStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDividendDistributionPercentOfTotalDistributions_019d1bac-cb47-7d67-a8bc-18fbdc139860" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDividendDistributionPercentOfTotalDistributions"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDistributionLongTermCapitalGainPercentOfTotalDistributions_019d1bac-cb47-7154-94d1-b8b99015083b" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDistributionLongTermCapitalGainPercentOfTotalDistributions"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_InvestmentCompanyDividendDistributionPercentOfTotalDistributions_019d1bac-cb47-7d67-a8bc-18fbdc139860" xlink:to="loc_fsk_InvestmentCompanyDistributionLongTermCapitalGainPercentOfTotalDistributions_019d1bac-cb47-7154-94d1-b8b99015083b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDistributionShortTermCapitalGainPercentOfTotalDistributions_019d1bac-cb47-7b87-a2b6-d33e39cd0ad0" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDistributionShortTermCapitalGainPercentOfTotalDistributions"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_InvestmentCompanyDividendDistributionPercentOfTotalDistributions_019d1bac-cb47-7d67-a8bc-18fbdc139860" xlink:to="loc_fsk_InvestmentCompanyDistributionShortTermCapitalGainPercentOfTotalDistributions_019d1bac-cb47-7b87-a2b6-d33e39cd0ad0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDistributionOrdinaryIncomePercentOfTotalDistributions_019d1bac-cb47-795f-93a6-4e6986b200ba" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDistributionOrdinaryIncomePercentOfTotalDistributions"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_InvestmentCompanyDividendDistributionPercentOfTotalDistributions_019d1bac-cb47-7d67-a8bc-18fbdc139860" xlink:to="loc_fsk_InvestmentCompanyDistributionOrdinaryIncomePercentOfTotalDistributions_019d1bac-cb47-795f-93a6-4e6986b200ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyTaxReturnOfCapitalDistributionPercentOfTotalDistributions_019d1bac-cb47-73e4-8c0c-3326b5f2e45d" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyTaxReturnOfCapitalDistributionPercentOfTotalDistributions"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_InvestmentCompanyDividendDistributionPercentOfTotalDistributions_019d1bac-cb47-7d67-a8bc-18fbdc139860" xlink:to="loc_fsk_InvestmentCompanyTaxReturnOfCapitalDistributionPercentOfTotalDistributions_019d1bac-cb47-73e4-8c0c-3326b5f2e45d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7170-bee3-2261e6c741f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyDividendDistribution"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyDistributionOrdinaryIncome_019d1bac-cb47-797f-8760-ac62f8e8c362" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyDistributionOrdinaryIncome"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7170-bee3-2261e6c741f8" xlink:to="loc_us-gaap_InvestmentCompanyDistributionOrdinaryIncome_019d1bac-cb47-797f-8760-ac62f8e8c362" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyDistributionLongTermCapitalGain_019d1bac-cb47-7568-8d9c-a8e0f7ef3db8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyDistributionLongTermCapitalGain"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7170-bee3-2261e6c741f8" xlink:to="loc_us-gaap_InvestmentCompanyDistributionLongTermCapitalGain_019d1bac-cb47-7568-8d9c-a8e0f7ef3db8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyTaxReturnOfCapitalDistribution_019d1bac-cb47-76a9-85ff-deb2333b4bcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyTaxReturnOfCapitalDistribution"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7170-bee3-2261e6c741f8" xlink:to="loc_us-gaap_InvestmentCompanyTaxReturnOfCapitalDistribution_019d1bac-cb47-76a9-85ff-deb2333b4bcc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDistributionShortTermCapitalGain_019d1bac-cb47-7793-a0b6-95001d456a22" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDistributionShortTermCapitalGain"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyDividendDistribution_019d1bac-cb47-7170-bee3-2261e6c741f8" xlink:to="loc_fsk_InvestmentCompanyDistributionShortTermCapitalGain_019d1bac-cb47-7793-a0b6-95001d456a22" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/InvestmentPortfolioScheduleofBalanceSheetInformationforCOPJVDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#InvestmentPortfolioScheduleofBalanceSheetInformationforCOPJVDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/InvestmentPortfolioScheduleofBalanceSheetInformationforCOPJVDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019d1bac-cb48-7606-aefd-42de9fd80c4d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019d1bac-cb48-7542-8204-c453cefddee3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb48-7606-aefd-42de9fd80c4d" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019d1bac-cb48-7542-8204-c453cefddee3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtFairValue_019d1bac-cb48-728f-8733-c98df8b6d524" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentOwnedAtFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019d1bac-cb48-7606-aefd-42de9fd80c4d" xlink:to="loc_us-gaap_InvestmentOwnedAtFairValue_019d1bac-cb48-728f-8733-c98df8b6d524" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019d1bac-cb48-7c66-b15e-08407791367b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_019d1bac-cb48-76bf-83e6-736e6a8a04ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb48-7c66-b15e-08407791367b" xlink:to="loc_us-gaap_OtherLiabilities_019d1bac-cb48-76bf-83e6-736e6a8a04ed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_019d1bac-cb48-77f7-87a9-c919e669642a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtLongtermAndShorttermCombinedAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019d1bac-cb48-7c66-b15e-08407791367b" xlink:to="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_019d1bac-cb48-77f7-87a9-c919e669642a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/InvestmentPortfolioScheduleofOperationsInformationforCOPJVDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#InvestmentPortfolioScheduleofOperationsInformationforCOPJVDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/InvestmentPortfolioScheduleofOperationsInformationforCOPJVDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019d1bac-cbe8-753f-8c1d-8dea9234c6dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019d1bac-cbe8-7e1b-ba0f-da5293fbeb93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_019d1bac-cbe8-753f-8c1d-8dea9234c6dd" xlink:to="loc_us-gaap_RealizedAndUnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax_019d1bac-cbe8-7e1b-ba0f-da5293fbeb93" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncome_019d1bac-cbe8-7a61-94fa-a4e2bdc9ed41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ProfitLoss_019d1bac-cbe8-753f-8c1d-8dea9234c6dd" xlink:to="loc_us-gaap_NetInvestmentIncome_019d1bac-cbe8-7a61-94fa-a4e2bdc9ed41" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement_019d1bac-cbe8-7b72-a99e-29f8ba6b3ef4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_019d1bac-cbe8-7be8-b372-31889ede508b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement_019d1bac-cbe8-7b72-a99e-29f8ba6b3ef4" xlink:to="loc_us-gaap_InterestExpense_019d1bac-cbe8-7be8-b372-31889ede508b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestExpenseTransferAgentAndCustodianFees_019d1bac-cbe8-7074-a8da-7b0f88e55c8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoninterestExpenseTransferAgentAndCustodianFees"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement_019d1bac-cbe8-7b72-a99e-29f8ba6b3ef4" xlink:to="loc_us-gaap_NoninterestExpenseTransferAgentAndCustodianFees_019d1bac-cbe8-7074-a8da-7b0f88e55c8d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_AdministrativeServicesExpenses_019d1bac-cbe8-7965-b4ad-106908a0ad9d" xlink:href="fsk-20260331.xsd#fsk_AdministrativeServicesExpenses"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement_019d1bac-cbe8-7b72-a99e-29f8ba6b3ef4" xlink:to="loc_fsk_AdministrativeServicesExpenses_019d1bac-cbe8-7965-b4ad-106908a0ad9d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_019d1bac-cbe8-742f-ab4e-ea27ce5fda13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfessionalFees"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement_019d1bac-cbe8-7b72-a99e-29f8ba6b3ef4" xlink:to="loc_us-gaap_ProfessionalFees_019d1bac-cbe8-742f-ab4e-ea27ce5fda13" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019d1bac-cbe8-725e-86ae-d247ebe151d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherGeneralAndAdministrativeExpense"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement_019d1bac-cbe8-7b72-a99e-29f8ba6b3ef4" xlink:to="loc_us-gaap_OtherGeneralAndAdministrativeExpense_019d1bac-cbe8-725e-86ae-d247ebe151d7" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/FinancialInstrumentsScheduleofDerivativeInstrumentsFairValueDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#FinancialInstrumentsScheduleofDerivativeInstrumentsFairValueDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/FinancialInstrumentsScheduleofDerivativeInstrumentsFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019d1bac-cbe9-7848-abdc-abf210f42bd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019d1bac-cbe9-7836-b109-5cb0cf464563" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019d1bac-cbe9-7848-abdc-abf210f42bd4" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019d1bac-cbe9-7836-b109-5cb0cf464563" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019d1bac-cbe9-7304-9d69-a030b1b7d558" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement_019d1bac-cbe9-7848-abdc-abf210f42bd4" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019d1bac-cbe9-7304-9d69-a030b1b7d558" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/FinancialInstrumentsScheduleofNetRealizedandUnrealizedGainsandLossesonDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#FinancialInstrumentsScheduleofNetRealizedandUnrealizedGainsandLossesonDerivativeInstrumentsDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/FinancialInstrumentsScheduleofNetRealizedandUnrealizedGainsandLossesonDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019d1bac-cbe9-7eaf-9e7b-7902c8c4741c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_019d1bac-cbe9-717c-ae7e-4c27d3a2d592" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019d1bac-cbe9-7eaf-9e7b-7902c8c4741c" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_019d1bac-cbe9-717c-ae7e-4c27d3a2d592" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfDerivatives_019d1bac-cbe9-780c-9959-97649c59e977" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfDerivatives"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019d1bac-cbe9-7eaf-9e7b-7902c8c4741c" xlink:to="loc_us-gaap_GainLossOnSaleOfDerivatives_019d1bac-cbe9-780c-9959-97649c59e977" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/FinancialInstrumentsScheduleofGrossAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#FinancialInstrumentsScheduleofGrossAssetsandLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/FinancialInstrumentsScheduleofGrossAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019d1bac-cbe9-7899-bbcd-d1bcad7b3947" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019d1bac-cbe9-7c56-9959-bc0c25ca468d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019d1bac-cbe9-7899-bbcd-d1bcad7b3947" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019d1bac-cbe9-7c56-9959-bc0c25ca468d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019d1bac-cbe9-7168-8be6-df0f06aea607" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019d1bac-cbe9-7899-bbcd-d1bcad7b3947" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019d1bac-cbe9-7168-8be6-df0f06aea607" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralObligationToReturnCash_019d1bac-cbe9-71d6-a1e7-641a5a0773b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeCollateralObligationToReturnCash"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019d1bac-cbe9-7899-bbcd-d1bcad7b3947" xlink:to="loc_us-gaap_DerivativeCollateralObligationToReturnCash_019d1bac-cbe9-71d6-a1e7-641a5a0773b0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralObligationToReturnSecurities_019d1bac-cbe9-71e8-ac07-030fa855889d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeCollateralObligationToReturnSecurities"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_019d1bac-cbe9-7899-bbcd-d1bcad7b3947" xlink:to="loc_us-gaap_DerivativeCollateralObligationToReturnSecurities_019d1bac-cbe9-71e8-ac07-030fa855889d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019d1bac-cbe9-70df-8940-fb45fc972922" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019d1bac-cbe9-7b20-a65e-cb86d37b0165" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019d1bac-cbe9-70df-8940-fb45fc972922" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019d1bac-cbe9-7b20-a65e-cb86d37b0165" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralRightToReclaimCash_019d1bac-cbe9-7688-9bf6-94d7fe00cee5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeCollateralRightToReclaimCash"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019d1bac-cbe9-70df-8940-fb45fc972922" xlink:to="loc_us-gaap_DerivativeCollateralRightToReclaimCash_019d1bac-cbe9-7688-9bf6-94d7fe00cee5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019d1bac-cbe9-791f-9d37-ad1f65c9d7bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019d1bac-cbe9-70df-8940-fb45fc972922" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019d1bac-cbe9-791f-9d37-ad1f65c9d7bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimSecurities_019d1bac-cbe9-734c-a5f6-30ef15f73c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimSecurities"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_019d1bac-cbe9-70df-8940-fb45fc972922" xlink:to="loc_us-gaap_DerivativeLiabilitySecuritiesSoldUnderAgreementsToResellSecuritiesLoanedCollateralRightToReclaimSecurities_019d1bac-cbe9-734c-a5f6-30ef15f73c9a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/FinancingArrangementsScheduleofInterestExpenseDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#FinancingArrangementsScheduleofInterestExpenseDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/FinancingArrangementsScheduleofInterestExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019d1bac-cbe9-7585-a066-efc91859d6a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebtExcludingAmortization_019d1bac-cbe9-7ea6-bdd5-63c4ee8f2b99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseDebtExcludingAmortization"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpenseDebt_019d1bac-cbe9-7585-a066-efc91859d6a9" xlink:to="loc_us-gaap_InterestExpenseDebtExcludingAmortization_019d1bac-cbe9-7ea6-bdd5-63c4ee8f2b99" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_019d1bac-cbe9-7af6-bbf8-515c95bae440" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpenseDebt_019d1bac-cbe9-7585-a066-efc91859d6a9" xlink:to="loc_us-gaap_AmortizationOfDebtDiscountPremium_019d1bac-cbe9-7af6-bbf8-515c95bae440" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://fskkrcapitalcorp.com/role/FinancialHighlightsScheduleofFinancialHighlightsDetails" xlink:type="simple" xlink:href="fsk-20260331.xsd#FinancialHighlightsScheduleofFinancialHighlightsDetails"/>
  <link:calculationLink xlink:role="http://fskkrcapitalcorp.com/role/FinancialHighlightsScheduleofFinancialHighlightsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyCapitalShareTransactionPerShare_019d1bac-cbe9-7e20-a7ad-d0b10af22ceb" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyCapitalShareTransactionPerShare"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyRepurchaseOfSharesPerShare_019d1bac-cbe9-75ea-a7e1-381ad9c40738" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyRepurchaseOfSharesPerShare"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_fsk_InvestmentCompanyCapitalShareTransactionPerShare_019d1bac-cbe9-7e20-a7ad-d0b10af22ceb" xlink:to="loc_us-gaap_InvestmentCompanyRepurchaseOfSharesPerShare_019d1bac-cbe9-75ea-a7e1-381ad9c40738" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyDistributionToShareholdersPerShare_019d1bac-cbe9-70fb-a774-00ae17df444b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyDistributionToShareholdersPerShare"/>
    <link:loc xlink:type="locator" xlink:label="loc_fsk_InvestmentCompanyDistributionToShareholderFromNetInvestmentIncome_019d1bac-cbe9-72b5-87be-bfcdb98f7291" xlink:href="fsk-20260331.xsd#fsk_InvestmentCompanyDistributionToShareholderFromNetInvestmentIncome"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyDistributionToShareholdersPerShare_019d1bac-cbe9-70fb-a774-00ae17df444b" xlink:to="loc_fsk_InvestmentCompanyDistributionToShareholderFromNetInvestmentIncome_019d1bac-cbe9-72b5-87be-bfcdb98f7291" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyRealizedGainLossOnInvestmentPerShare_019d1bac-cbe9-78ae-9a5b-49345e176445" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyRealizedGainLossOnInvestmentPerShare"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentCompanyDistributionToShareholdersPerShare_019d1bac-cbe9-70fb-a774-00ae17df444b" xlink:to="loc_us-gaap_InvestmentCompanyRealizedGainLossOnInvestmentPerShare_019d1bac-cbe9-78ae-9a5b-49345e176445" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare_019d1bac-cbe9-7f78-826a-93696ea49104" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare_019d1bac-cbe9-7eb2-bcc2-2195fbd61ab8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cbe9-7f78-826a-93696ea49104" xlink:to="loc_us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare_019d1bac-cbe9-7eb2-bcc2-2195fbd61ab8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare_019d1bac-cbe9-7710-9675-bc8c37fcf5cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.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_019d1bac-cbe9-7f78-826a-93696ea49104" xlink:to="loc_us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare_019d1bac-cbe9-7710-9675-bc8c37fcf5cf" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
