HELOC Repayment Calculator — Draw Period vs. Repayment Period
Estimate how your HELOC payment changes when the interest-only draw period ends and the fully amortizing repayment period begins. See the total interest and payment increase.
HELOC payment change by repayment-period rate
Example: $80,000 credit limit, $40,000 initial draw, no additional draws, 10-year draw period at 9.00%, 20-year repayment period. Values are rounded estimates.
| Repayment-period rate | End-of-draw monthly payment | Start-of-repayment monthly payment | Payment increase |
|---|---|---|---|
| 7.00% | $300 | $310 | +$10 |
| 9.00% | $300 | $360 | +$60 |
| 11.00% | $300 | $413 | +$113 |
Tips for estimating a HELOC
- Because the draw period is interest-only, the principal never falls on its own — always check how much the payment jumps the moment repayment begins.
- Most HELOCs carry a variable rate, so run the draw and repayment periods at different rates and see how much a rate increase would add to your payment.
- If you plan additional draws, watch for the point where the balance reaches the credit limit — no further draws are possible once the limit is hit.
- A longer repayment period lowers the monthly payment but increases total interest, so pick a term you can sustain rather than the lowest payment.
HELOC questions
Side Note — Watch for HELOC "payment shock"
A HELOC is a revolving credit line secured by home equity — you borrow only what you need, similar to a credit card. Most products have two phases: a draw period, when only interest is due, and a repayment period, when the balance is paid off in full. Because the draw-period payment covers interest only, the principal never shrinks on its own, so the moment the draw period ends and repayment begins, the entire balance must be amortized — often causing the monthly payment to rise sharply. This jump is commonly called "payment shock."
Most HELOCs also carry a variable rate tied to an index such as the prime rate. A rate increase during the draw period raises the interest-only payment, and the rate level when repayment begins has a large effect on the new fully amortizing payment. That is why this calculator lets you enter separate rates for the draw period and the repayment period.
When evaluating a HELOC, it helps to model the draw-period length, the balance you expect at the start of repayment, and the rate you expect at that time together, so you are not surprised by the payment shock. Real contracts differ in rate caps, minimum payments, and fee structures, so confirm the final numbers against the lender's official disclosure.