HELOC Calculator
Calculate your Home Equity Line of Credit payments for both the draw period (interest-only) and repayment period.
Calculate your Home Equity Line of Credit payments for both the interest-only draw period and the fully amortizing repayment period, and see how a rate change affects your costs.
How HELOC Calculator Works
A HELOC has two distinct phases. During the draw period, most HELOCs only require interest-only payments on the amount you've borrowed: Monthly Payment = Credit Line Balance × (Annual Rate ÷ 12) — no principal is required, so the balance doesn't shrink on its own during this phase.
Once the draw period ends, the HELOC enters the repayment period, where the outstanding balance is amortized like a standard loan over the remaining years, using the usual payment formula — this is when payments typically jump substantially, since you're now paying down principal in addition to interest.
Your available credit line is capped by the lender's maximum combined loan-to-value ratio, just like a home equity loan: Home Value × Max LTV% − Existing Mortgage Balance. The rate change scenario recalculates both the draw-period and repayment-period payments at a higher or lower rate, illustrating how exposed a variable-rate HELOC is to rate movements.
See It In Action
Who Uses HELOC Calculator and Why
- Estimating the interest-only payment during a HELOC\'s draw period on a specific balance you plan to borrow.
- Seeing how much your payment would jump once the HELOC enters its repayment period and starts amortizing.
- Checking your available credit line against a lender\'s typical combined loan-to-value limit.
- Stress-testing how a rate increase would affect payments in both the draw period and repayment period of a variable-rate HELOC.
Mistakes to Avoid
- Assuming the draw-period payment gives an accurate picture of the loan\'s full cost — because most HELOCs only require interest-only payments during the draw period, the balance doesn\'t shrink on its own, and the repayment-period payment (once principal is included) is typically substantially higher.
- Treating a HELOC\'s rate as fixed — most HELOCs carry a variable rate tied to a benchmark like the prime rate, meaning both draw-period and repayment-period payments can change over time as rates move, unlike a fixed-rate home equity loan.
- Not accounting for the same CLTV cap that applies to home equity loans — your available credit line is capped the same way (Home Value × Max LTV% minus existing mortgage balance), so a HELOC request can also be limited or denied based on this ratio.
Tips for Best Results
- Even though interest-only payments aren\'t required during the draw period, making voluntary principal payments reduces your balance, frees up available credit, and lowers the payment shock once repayment begins.
- Run the rate-change scenario even if current rates seem stable — it shows how exposed your specific balance and repayment schedule are to future rate movements, which matters most for a variable-rate product like a HELOC.
Fixing Common Problems
My payment jumped a lot once I modeled the repayment period. — This is expected and normal — the draw period is typically interest-only, so the balance never shrinks on its own, while the repayment period amortizes the full outstanding balance like a standard loan, adding principal repayment on top of interest.
Terms Explained
Draw period: The phase of a HELOC where you can borrow against the credit line, typically requiring only interest-only payments.
Repayment period: The phase after the draw period ends, where the outstanding balance is amortized like a standard installment loan.