HELOC Calculator
Estimate HELOC interest-only draw payment, repayment payment, utilization, payoff time and interest impact of extra payments.
- Separates draw-period and repayment-period payments
- Shows credit-line utilization
- Simulates optional extra repayment principal
Calculator workspace
Change any assumption and recalculate. Your entries stay in this browser unless you choose to share or copy a result.
What this HELOC Calculator calculates
A home-equity line of credit often behaves differently in its draw and repayment phases. During an interest-only draw period, the minimum payment may cover only current interest on the balance. When repayment begins, the outstanding balance can convert to a much larger amortizing payment. This calculator shows both amounts side by side and can simulate how an extra repayment amount changes payoff time and interest.
The result is intentionally more than a single number. Supporting figures are shown beside the headline answer so you can see which part of the calculation is driving the outcome. This makes the tool useful for scenario testing: change one assumption, calculate again, and compare the supporting values rather than relying on a black-box result.
Formula and calculation method
Interest-only draw payment = balance × monthly rate; repayment uses fixed-rate amortization of the drawn balance.
Inputs are validated before calculation and the arithmetic runs locally in the browser. Monetary fields use the selected currency only for display formatting. The calculator does not retrieve bank, payroll, property, medical, market or exchange-rate data from an external service.
How to use it
- Enter values that describe the same scenario and reporting period.
- Keep percentages and units consistent with the labels shown beside each input.
- Select Calculate and review both the headline result and the supporting metrics.
- Change one assumption at a time to understand sensitivity instead of accepting a single scenario.
- Use Copy Result, Share Result or Save Result Image when you need to keep a record of the calculation.
Worked example
With a 100,000 line and 40,000 currently drawn at 8.5%, the interest-only draw payment is based on the 40,000 balance. If that same balance later amortizes over 15 years, the repayment payment is significantly different. Add 100 extra per month to see the potential reduction in repayment time and interest.
How to interpret the result
The utilization percentage shows how much of the available line is currently used. For variable-rate HELOCs, payment risk can be meaningful because a higher future rate increases both interest-only and amortizing payments. Stress-test the calculator with higher rates rather than relying only on today’s rate.
For an important decision, compare the output with original documents, lender or employer terms, supplier information, professional guidance, or other authoritative records relevant to the calculation. Small differences in rates, timing, fees and definitions can materially change a result even when the formula itself is correct.
Important assumptions and limitations
Most HELOCs have variable rates and lender-specific minimum-payment rules. This calculator holds the entered rate constant, assumes no new draws or fees, and assumes the balance remains unchanged during the interest-only draw-period estimate. It does not model rate caps, floors, annual fees, early-closure fees, or a balloon structure.
This calculator is for planning, checking, education and general informational use. It is designed to make assumptions visible and calculations reproducible, but it does not replace a contract, disclosure, professional opinion, medical assessment, accounting policy or lending decision.
Frequently asked questions
Why is the repayment payment higher than the draw payment?
Interest-only draw payments do not reduce principal, while repayment payments must pay both interest and principal over a finite term.
Can I enter the full credit limit as the balance?
Yes, as long as the drawn balance is not greater than the limit.
Does the calculator assume a variable rate?
No. It uses the rate you enter as a constant scenario so you can test different rates manually.