<?xml version="1.0" encoding="US-ASCII"?>
<!-- DFIN New ActiveDisclosure (SM) XBRL Linkbase Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2022-11-01T14:03:02.2508+00:00 -->
<!-- Copyright (c) 2022 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" 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">
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_StatementConsolidatedBalanceSheetsUnaudited" xlink:href="tslx-20220930.xsd#Role_StatementConsolidatedBalanceSheetsUnaudited" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_StatementConsolidatedStatementsOfOperationsUnaudited" xlink:href="tslx-20220930.xsd#Role_StatementConsolidatedStatementsOfOperationsUnaudited" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/StatementConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="tslx-20220930.xsd#StatementConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_DisclosureDerivativesSummaryOfAmountsPaidAndReceivedOnInterestRateSwapTransactionsExcludingUpfrontFeesDetails" xlink:href="tslx-20220930.xsd#Role_DisclosureDerivativesSummaryOfAmountsPaidAndReceivedOnInterestRateSwapTransactionsExcludingUpfrontFeesDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_DisclosureFairValueOfFinancialInstrumentsFairValueMeasurementsOfInvestmentsDetails" xlink:href="tslx-20220930.xsd#Role_DisclosureFairValueOfFinancialInstrumentsFairValueMeasurementsOfInvestmentsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_DisclosureDebtScheduleOfComponentsOfInterestExpenseDetails" xlink:href="tslx-20220930.xsd#Role_DisclosureDebtScheduleOfComponentsOfInterestExpenseDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/DisclosureDebtScheduleOfComponentOfCarryingValueOfConvertibleNotesAndInterestRatesDetails" xlink:href="tslx-20220930.xsd#DisclosureDebtScheduleOfComponentOfCarryingValueOfConvertibleNotesAndInterestRatesDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/DisclosureEarningsPerShareComputationOfBasicAndDilutedEarningsPerCommonShareDetails" xlink:href="tslx-20220930.xsd#DisclosureEarningsPerShareComputationOfBasicAndDilutedEarningsPerCommonShareDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/DisclosureFinancialHighlightsSummaryOfFinancialHighlightsForOneShareCommonStockOutstandingDetails" xlink:href="tslx-20220930.xsd#DisclosureFinancialHighlightsSummaryOfFinancialHighlightsForOneShareCommonStockOutstandingDetails" xlink:type="simple"/>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_StatementConsolidatedBalanceSheetsUnaudited">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNet" xlink:to="us-gaap_PreferredStockValue" order="0" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_Liabilities" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_LongTermDebt" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_InvestmentOwnedAtFairValue" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNet" xlink:to="us-gaap_CommonStockValue" order="1" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_CommitmentsAndContingencies" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_ManagementFeePayable" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_AssetsNet" order="2" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNet" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock" order="2" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="tslx_IncentiveFeesOnNetInvestmentIncomePayableToAffiliate" order="2" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_InterestReceivable" order="2" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNet" xlink:to="us-gaap_TreasuryStockValue" order="3" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="tslx_IncentiveFeesOnNetCapitalGainsAccruedToAffiliate" order="3" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_PrepaidExpenseAndOtherAssets" order="3" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsNet" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="4" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_DividendsPayableCurrentAndNoncurrent" order="4" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_DueToAffiliateCurrentAndNoncurrent" order="5" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_OtherLiabilities" order="6" weight="1.00" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsNet" xlink:label="us-gaap_AssetsNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockValue" xlink:label="us-gaap_PreferredStockValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentOwnedAtFairValue" xlink:label="us-gaap_InvestmentOwnedAtFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="us-gaap_CommitmentsAndContingencies"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ManagementFeePayable" xlink:label="us-gaap_ManagementFeePayable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncentiveFeesOnNetInvestmentIncomePayableToAffiliate" xlink:label="tslx_IncentiveFeesOnNetInvestmentIncomePayableToAffiliate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestReceivable" xlink:label="us-gaap_InterestReceivable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValue" xlink:label="us-gaap_TreasuryStockValue"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncentiveFeesOnNetCapitalGainsAccruedToAffiliate" xlink:label="tslx_IncentiveFeesOnNetCapitalGainsAccruedToAffiliate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrepaidExpenseAndOtherAssets" xlink:label="us-gaap_PrepaidExpenseAndOtherAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent" xlink:label="us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DueToAffiliateCurrentAndNoncurrent" xlink:label="us-gaap_DueToAffiliateCurrentAndNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherLiabilities" xlink:label="us-gaap_OtherLiabilities"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_StatementConsolidatedStatementsOfOperationsUnaudited">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetRealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:to="us-gaap_RealizedInvestmentGainsLosses" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyRealizedAndUnrealizedGainLossOnInvestmentAndForeignCurrency" xlink:to="tslx_NetChangeInUnrealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetChangeInUnrealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:to="us-gaap_UnrealizedGainLossOnInvestments" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_InvestmentIncomeInterest" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_InterestExpense" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetExpense" xlink:to="us-gaap_OperatingExpenses" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetsFromOperationsIncreaseDecrease" xlink:to="us-gaap_InvestmentIncomeNet" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentIncomeNet" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NonoperatingIncomeExpense" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetRealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:to="us-gaap_GainLossOnSaleOfDerivatives" order="1" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetChangeInUnrealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossUnrealized" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_InvestmentIncomeDividend" order="1" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_ManagementFeeExpense" order="1" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentIncomeNet" xlink:to="us-gaap_IncomeTaxExpenseBenefit" order="1" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="tslx_NetExpense" order="1" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetExpense" xlink:to="tslx_ManagementFeeWaived" order="1" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetRealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossRealized" order="2" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyRealizedAndUnrealizedGainLossOnInvestmentAndForeignCurrency" xlink:to="tslx_NetRealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" order="2" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_NetChangeInUnrealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:to="us-gaap_UnrealizedGainLossOnDerivatives" order="2" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetsFromOperationsIncreaseDecrease" xlink:to="us-gaap_InvestmentCompanyRealizedAndUnrealizedGainLossOnInvestmentAndForeignCurrency" order="2" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_OtherNonoperatingIncome" order="2" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="tslx_IncentiveFeesOnNetInvestmentIncome" order="2" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="tslx_IncentiveFeesOnNetCapitalGains" order="3" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_ProfessionalFees" order="4" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_NoninterestExpenseDirectorsFees" order="5" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_OtherGeneralAndAdministrativeExpense" order="6" weight="1" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_NetRealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:label="tslx_NetRealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RealizedInvestmentGainsLosses" xlink:label="us-gaap_RealizedInvestmentGainsLosses"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyRealizedAndUnrealizedGainLossOnInvestmentAndForeignCurrency" xlink:label="us-gaap_InvestmentCompanyRealizedAndUnrealizedGainLossOnInvestmentAndForeignCurrency"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_NetChangeInUnrealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation" xlink:label="tslx_NetChangeInUnrealizedGainsLossesOnInvestmentsAndForeignCurrencyTranslation"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrealizedGainLossOnInvestments" xlink:label="us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="us-gaap_InvestmentIncomeInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingExpenses" xlink:label="us-gaap_OperatingExpenses"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_NetExpense" xlink:label="tslx_NetExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyNetAssetsFromOperationsIncreaseDecrease" xlink:label="us-gaap_InvestmentCompanyNetAssetsFromOperationsIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentIncomeNet" xlink:label="us-gaap_InvestmentIncomeNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSaleOfDerivatives" xlink:label="us-gaap_GainLossOnSaleOfDerivatives"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentIncomeDividend" xlink:label="us-gaap_InvestmentIncomeDividend"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ManagementFeeExpense" xlink:label="us-gaap_ManagementFeeExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_ManagementFeeWaived" xlink:label="tslx_ManagementFeeWaived"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossRealized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrealizedGainLossOnDerivatives" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherNonoperatingIncome" xlink:label="us-gaap_OtherNonoperatingIncome"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncentiveFeesOnNetInvestmentIncome" xlink:label="tslx_IncentiveFeesOnNetInvestmentIncome"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncentiveFeesOnNetCapitalGains" xlink:label="tslx_IncentiveFeesOnNetCapitalGains"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfessionalFees" xlink:label="us-gaap_ProfessionalFees"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NoninterestExpenseDirectorsFees" xlink:label="us-gaap_NoninterestExpenseDirectorsFees"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherGeneralAndAdministrativeExpense" xlink:label="us-gaap_OtherGeneralAndAdministrativeExpense"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/StatementConsolidatedStatementsOfCashFlowsUnaudited">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_ProfitLoss" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromShortTermDebt" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_RepaymentsOfShortTermDebt" order="1" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_UnrealizedGainLossOnInvestments" order="1" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfFinancingCosts" order="2" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_NetRealizedGainsLossesOnForeignCurrencyTransactions" order="3" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="3" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_RepaymentsOfConvertibleDebt" order="4" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossUnrealized" order="4" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsForRepurchaseOfCommonStock" order="5" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_UnrealizedGainLossOnDerivatives" order="5" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_RealizedInvestmentGainsLosses" order="6" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfDividends" order="7" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_GainLossOnSaleOfDerivatives" order="8" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments" order="9" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_AmortizationOfFinancingCosts" order="10" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_AmortizationOfDebtDiscountPremium" order="11" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_PurchasesAndOriginationsOfInvestmentsNet" order="12" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_GainLossFormAdjustmentOfPaidInKindInterest" order="13" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_ProceedsFromInvestmentsNet" order="14" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_RepaymentsOnInvestments" order="15" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet" order="17" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_IncreaseDecreaseInInterestReceivablePaidInKind" order="18" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" order="19" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_IncreaseDecreaseInManagementFeesPayableToAffiliate" order="20" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_IncreaseDecreaseInIncentiveFeesOnNetInvestmentIncomePayableToAffiliate" order="21" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="tslx_IncreaseDecreaseInIncentiveFeesOnNetCapitalGainsAccruedToAffiliate" order="22" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent" order="23" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" order="24" weight="1.00" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromShortTermDebt" xlink:label="us-gaap_ProceedsFromShortTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfShortTermDebt" xlink:label="us-gaap_RepaymentsOfShortTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrealizedGainLossOnInvestments" xlink:label="us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="us-gaap_PaymentsOfFinancingCosts"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_NetRealizedGainsLossesOnForeignCurrencyTransactions" xlink:label="tslx_NetRealizedGainsLossesOnForeignCurrencyTransactions"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfConvertibleDebt" xlink:label="us-gaap_RepaymentsOfConvertibleDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrealizedGainLossOnDerivatives" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RealizedInvestmentGainsLosses" xlink:label="us-gaap_RealizedInvestmentGainsLosses"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsOfDividends" xlink:label="us-gaap_PaymentsOfDividends"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSaleOfDerivatives" xlink:label="us-gaap_GainLossOnSaleOfDerivatives"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments" xlink:label="us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="us-gaap_AmortizationOfFinancingCosts"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_PurchasesAndOriginationsOfInvestmentsNet" xlink:label="tslx_PurchasesAndOriginationsOfInvestmentsNet"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_GainLossFormAdjustmentOfPaidInKindInterest" xlink:label="tslx_GainLossFormAdjustmentOfPaidInKindInterest"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_ProceedsFromInvestmentsNet" xlink:label="tslx_ProceedsFromInvestmentsNet"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_RepaymentsOnInvestments" xlink:label="tslx_RepaymentsOnInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet" xlink:label="us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncreaseDecreaseInInterestReceivablePaidInKind" xlink:label="tslx_IncreaseDecreaseInInterestReceivablePaidInKind"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncreaseDecreaseInManagementFeesPayableToAffiliate" xlink:label="tslx_IncreaseDecreaseInManagementFeesPayableToAffiliate"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncreaseDecreaseInIncentiveFeesOnNetInvestmentIncomePayableToAffiliate" xlink:label="tslx_IncreaseDecreaseInIncentiveFeesOnNetInvestmentIncomePayableToAffiliate"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_IncreaseDecreaseInIncentiveFeesOnNetCapitalGainsAccruedToAffiliate" xlink:label="tslx_IncreaseDecreaseInIncentiveFeesOnNetCapitalGainsAccruedToAffiliate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent" xlink:label="us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_DisclosureDerivativesSummaryOfAmountsPaidAndReceivedOnInterestRateSwapTransactionsExcludingUpfrontFeesDetails">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_PaymentsForProceedsFromHedgeInvestingActivities" xlink:to="us-gaap_PaymentsForHedgeInvestingActivities" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_PaymentsForProceedsFromHedgeInvestingActivities" xlink:to="us-gaap_ProceedsFromHedgeInvestingActivities" order="1" weight="-1.00" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsForProceedsFromHedgeInvestingActivities" xlink:label="us-gaap_PaymentsForProceedsFromHedgeInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsForHedgeInvestingActivities" xlink:label="us-gaap_PaymentsForHedgeInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromHedgeInvestingActivities" xlink:label="us-gaap_ProceedsFromHedgeInvestingActivities"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_DisclosureFairValueOfFinancialInstrumentsFairValueMeasurementsOfInvestmentsDetails">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_InvestmentsFairValueDisclosureNet" xlink:to="us-gaap_InvestmentsFairValueDisclosure" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentsFairValueDisclosure" xlink:to="us-gaap_TradingSecuritiesDebt" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="tslx_InvestmentsFairValueDisclosureNet" xlink:to="tslx_InterestRateSwaps" order="1" weight="-1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentsFairValueDisclosure" xlink:to="tslx_EquityAndOtherInvestments" order="1" weight="1" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_InvestmentsFairValueDisclosureNet" xlink:label="tslx_InvestmentsFairValueDisclosureNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentsFairValueDisclosure" xlink:label="us-gaap_InvestmentsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TradingSecuritiesDebt" xlink:label="us-gaap_TradingSecuritiesDebt"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_InterestRateSwaps" xlink:label="tslx_InterestRateSwaps"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_EquityAndOtherInvestments" xlink:label="tslx_EquityAndOtherInvestments"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/Role_DisclosureDebtScheduleOfComponentsOfInterestExpenseDetails">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDebtExpense" xlink:to="us-gaap_InterestExpenseDebt" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDebtExpense" xlink:to="us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts" order="2" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDebtExpense" xlink:to="us-gaap_AmortizationOfFinancingCosts" order="3" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDebtExpense" xlink:to="us-gaap_AmortizationOfDebtDiscountPremium" order="4" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDebtExpense" xlink:to="tslx_SwapSettlement" order="5" weight="-1.00" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestAndDebtExpense" xlink:label="us-gaap_InterestAndDebtExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseDebt" xlink:label="us-gaap_InterestExpenseDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts" xlink:label="us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="us-gaap_AmortizationOfFinancingCosts"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_SwapSettlement" xlink:label="tslx_SwapSettlement"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/DisclosureDebtScheduleOfComponentOfCarryingValueOfConvertibleNotesAndInterestRatesDetails">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebt" xlink:to="us-gaap_DebtInstrumentCarryingAmount" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebt" xlink:to="tslx_OriginalIssueDiscountNetOfAccretion" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebt" xlink:to="us-gaap_DeferredFinanceCostsNet" order="2" weight="-1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LongTermDebt" xlink:to="tslx_FairValueOfAnEffectiveHedge" order="3" weight="1.00" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="us-gaap_DebtInstrumentCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_OriginalIssueDiscountNetOfAccretion" xlink:label="tslx_OriginalIssueDiscountNetOfAccretion"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="us-gaap_DeferredFinanceCostsNet"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_FairValueOfAnEffectiveHedge" xlink:label="tslx_FairValueOfAnEffectiveHedge"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/DisclosureEarningsPerShareComputationOfBasicAndDilutedEarningsPerCommonShareDetails">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" order="0" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities" order="1" weight="1.00" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:to="tslx_AdjustmentForInterestExpenseAndDeferredFinancingCostsIncentiveFeeAndExciseTaxNet" order="1" weight="1.00" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities" xlink:label="us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_AdjustmentForInterestExpenseAndDeferredFinancingCostsIncentiveFeeAndExciseTaxNet" xlink:label="tslx_AdjustmentForInterestExpenseAndDeferredFinancingCostsIncentiveFeeAndExciseTaxNet"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://sixthstreetspecialtylending.com/20220930/taxonomy/role/DisclosureFinancialHighlightsSummaryOfFinancialHighlightsForOneShareCommonStockOutstandingDetails">
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease" xlink:to="us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare" xlink:to="us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare" order="0" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease" xlink:to="us-gaap_InvestmentCompanyDistributionToShareholdersPerShare" order="1" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare" xlink:to="us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare" order="1" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease" xlink:to="tslx_InvestmentCompanySettlementOfConvertibleNotesPerShare" order="2" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease" xlink:to="us-gaap_InvestmentCompanyRedemptionFeePerShare" order="3" weight="1" use="optional"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease" xlink:to="tslx_DividendsDeclaredFromNetInvestmentIncomePerShare" order="4" weight="1" use="optional"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease" xlink:label="us-gaap_InvestmentCompanyNetAssetValuePerSharePeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare" xlink:label="us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare" xlink:label="us-gaap_InvestmentCompanyInvestmentIncomeLossPerShare"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyDistributionToShareholdersPerShare" xlink:label="us-gaap_InvestmentCompanyDistributionToShareholdersPerShare"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare" xlink:label="us-gaap_InvestmentCompanyGainLossOnInvestmentPerShare"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_InvestmentCompanySettlementOfConvertibleNotesPerShare" xlink:label="tslx_InvestmentCompanySettlementOfConvertibleNotesPerShare"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentCompanyRedemptionFeePerShare" xlink:label="us-gaap_InvestmentCompanyRedemptionFeePerShare"/>
    <link:loc xlink:type="locator" xlink:href="tslx-20220930.xsd#tslx_DividendsDeclaredFromNetInvestmentIncomePerShare" xlink:label="tslx_DividendsDeclaredFromNetInvestmentIncomePerShare"/>
  </link:calculationLink>
</link:linkbase>
