How it works
The calculator separates a HELOC into two phases. During the draw period, it assumes the entire entered amount is outstanding and the required payment is interest-only. During the repayment period, no further borrowing occurs and the balance is repaid with level monthly principal-and-interest payments.
The model also estimates a maximum line from the home’s value, current mortgage balance, and the selected combined loan-to-value limit.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?creditLine=Amount drawnMoney · Required · Default: 50,000
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?annualRate=Interest ratePercentage · Required · Default: 8
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?drawYears=Draw periodNumber · Required · Default: 5
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?repaymentYears=Repayment periodNumber · Required · Default: 15
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?annualFee=Annual feeMoney · Optional · Default: 0
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?includeClosingCosts=Include closing costsTrue or false · Optional · Default: false
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?closingCostValue=Closing cost valueNumber · Required · Default: 2 · Used when includeClosingCosts = true
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?closingCostUnit=Closing cost unitChoice · Required · Default: percent · Accepted values: percent, amount · Used when includeClosingCosts = true
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?closingCostTreatment=Closing cost treatmentChoice · Required · Default: deducted · Accepted values: deducted, upfront · Used when includeClosingCosts = true
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?homeValue=Current home valueMoney · Required · Default: 500,000
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?mortgageBalance=Current mortgage balanceMoney · Required · Default: 210,000
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?maxLtv=Maximum combined LTVPercentage · Required · Default: 80
Outputs
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drawMonthlyPaymentDraw-period monthly outlayCurrency · Primary output
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repaymentMonthlyPaymentRepayment-period monthly outlayCurrency
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totalScheduledPaymentsTotal scheduled monthly outlaysCurrency
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totalInterestTotal interestCurrency
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totalFeesClosing + annual feesCurrency
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totalBorrowingCostInterest + feesCurrency
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cashReceivedProceeds receivedCurrency
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cashDueAtClosingCash due at closingCurrency
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estimatedAprCash-flow APR estimatePercentage
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estimatedCreditLimitLTV-based HELOC limitCurrency
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combinedLtvCombined LTV with this drawPercentage
Fees and closing costs
Annual fees are divided by twelve and added to each monthly outlay. Closing costs can be entered as a percentage or dollar amount and treated either as a deduction from proceeds or as cash paid upfront. The cash-flow APR estimate includes those entered costs for comparison, but it is not a lender disclosure.
Reading the payment change
The repayment-period payment is normally higher because it must reduce principal as well as cover interest. The chart keeps the balance flat through the draw years and then shows the modeled decline during repayment.
Important assumptions
This is a deliberately simplified comparison model. It assumes:
- the full line is drawn immediately;
- no principal is repaid or redrawn during the draw period;
- the interest rate never changes;
- annual fees remain constant; and
- all payments are made on schedule.
Real HELOCs may use variable rates, minimum-payment rules, introductory rates, transaction fees, inactivity fees, early-closure fees, or balloon payments. Review the lender’s disclosures and test a higher rate before relying on the payment estimate.