A HELOC has two distinct phases with very different payments. This shows both, side by side, so the jump between them is visible before it happens rather than after.
How it works
Two phases, two formulas
Draw period (interest-only): payment = balance × (rate ÷ 12)
Repayment period: payment = balance × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1)
Where a HELOC’s real risk lives
A borrower who only ever pays the low interest-only minimum during the draw period has not reduced the principal at all — so the repayment-period payment, calculated on the full original balance amortized over a much shorter remaining term, can be a large, sometimes startling jump. Showing both payments side by side is the entire point of this calculator; a single blended average would hide exactly the thing a HELOC borrower most needs to plan for.
Most HELOCs carry a variable rate
This calculator assumes the entered rate stays fixed. A real HELOC’s rate typically moves with a benchmark rate over its life — this shows the payment at one rate, not a forecast of what the rate will do over the loan’s full term.
How to use this calculator
- Enter the amount you’ve drawn (or plan to draw).
- Enter the current rate.
- Enter the repayment period length once the draw period ends.
Frequently asked questions
Why is the interest-only payment so much lower?
Because none of it goes toward the principal — you’re only covering that month’s interest charge, which is why the balance never shrinks during a draw period where only the minimum is paid.
Can I pay more than the interest-only minimum during the draw period?
Yes, and doing so reduces the balance the repayment period will later amortize — this calculator shows the minimum interest-only figure and the full repayment-period figure on the original balance; paying extra during the draw period would lower both the eventual repayment balance and its payment.
Why does the rate matter so much for a HELOC specifically?
Because most HELOCs are variable-rate, tied to a benchmark that moves over time — unlike a fixed-rate mortgage, the payment risk here includes not just the draw-to-repayment jump but potential rate changes on top of it.
What happens if I can’t afford the repayment-period payment?
This is exactly the risk this calculator exists to make visible ahead of time — talk to your lender about options well before the draw period ends if the repayment figure looks unaffordable, since refinancing or restructuring options are typically easier to arrange in advance than after payments are already due.
Is a HELOC the same as a home equity loan?
No — a home equity loan is typically a lump sum with a fixed repayment schedule from the start, more like the loan amortization calculator’s own shape. A HELOC is a revolving line of credit with the draw-then-repay structure this calculator models.
