HELOC Payment Calculator
Estimate HELOC Payment totals, payments, rates, and costs for financial planning.
This HELOC payment calculator estimates your monthly payment during both phases of a home equity line of credit: the interest-only draw period, and the fully amortizing repayment period once the draw period ends and the loan converts to principal-plus-interest payments.
Enter your outstanding balance, interest rate, and which phase you're in, and the calculator returns your estimated monthly payment.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| $30,000 drawn, 8.5% rate, during draw period | $212.50/month | Interest-only payment = $30,000 × (0.085 ÷ 12) = $30,000 × 0.0070833 = $212.50. |
| Same $30,000 balance entering a 15-year repayment period at 8.5% | ≈$295.47/month | Now fully amortizing over 180 months at the same rate: payment ≈ $295.47/month - about 39% higher than the $212.50 interest-only payment on the identical balance, illustrating the payment jump at the phase transition. |
Draw Period vs. Repayment Period
During the draw period (commonly 5-10 years), most HELOCs only require interest payments on the amount drawn, keeping payments low but not reducing the principal balance. Once the repayment period begins (commonly 10-20 years), payments become fully amortizing, covering both principal and interest - which often causes a significant payment increase compared to the draw period.
Why HELOC Payments Can Jump Sharply
Because draw-period payments are interest-only, the full principal balance remains untouched going into repayment. Combined with a HELOC's typically variable interest rate, borrowers can see a substantial payment increase when the loan transitions phases - planning for this jump in advance avoids payment shock.
How to Use the HELOC Payment Calculator
- Open the HELOC Payment Calculator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the heloc payment calculator works.
Frequently Asked Questions
How is a HELOC payment calculated during the draw period?
Most HELOCs charge interest-only payments during the draw period: multiply your outstanding balance by the (typically variable) interest rate divided by 12 for the monthly payment.
Why does my HELOC payment increase after the draw period?
Once the repayment period begins, payments convert to fully amortizing (principal plus interest) on the full outstanding balance, which is usually significantly higher than the interest-only payments during the draw period.
Is a HELOC interest rate fixed or variable?
Most HELOCs carry a variable interest rate tied to a benchmark like the prime rate, meaning your payment can change over time even before the repayment period begins - some lenders offer a fixed-rate conversion option for part of the balance.
How do I use this heloc payment calculator?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the HELOC Payment Calculator calculate?
Estimate HELOC Payment totals, payments, rates, and costs for financial planning. It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this heloc payment use?
The formula is: Draw Period: Payment = Balance × (Rate ÷ 12); Repayment Period: Standard Amortization Formula. The two-phase structure - interest-only, then fully amortizing - developed alongside the modern revolving line-of-credit product in the 1980s, designed to mimic a credit card's flexible draw-as-needed feature while still requiring the balance to be fully repaid by a fixed end date. This structure is also exactly why HELOC borrowers are sometimes caught off guard: the payment can rise sharply the moment the draw period ends and amortization begins on the full balance.
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Last updated: September 27, 2026.