How much will my HELOC payment be?
Your HELOC payment depends on how much of your credit line you draw, your CLTV (combined loan-to-value) cap, and your variable rate. During the draw period, most HELOCs charge interest only on the amount you have actually borrowed. Once the draw period ends, the repayment period begins and your payment rises because it now includes both principal and interest, amortized over the remaining term. Use the calculator below to estimate your own numbers.
Last updated July 20, 2026How is my HELOC credit line calculated?
Lenders calculate your available HELOC credit line from your home’s value, your existing mortgage balance, and a maximum combined loan-to-value (CLTV) percentage they’re willing to lend against — commonly in the 80–90% range, though the exact cap varies by lender, credit profile, and property type. The formula is:
Available credit line = (Home value × CLTV cap) − Current mortgage balance
Enter your own numbers below to see your estimated credit line, your interest-only payment during the draw period, and your fully amortizing payment once repayment begins.
Cannot exceed your available credit line.
What will I pay during the draw period?
During the draw period (typically 5–10 years), most HELOCs are interest-only: your required monthly payment is just the interest that accrued on whatever balance you have actually drawn, not the full credit line. Drawing less keeps this payment lower; you can also choose to pay down principal voluntarily during this period even though it isn’t required.
Because the rate is variable, this payment moves when the index it’s tied to moves — the calculator above uses the rate you enter as a snapshot, not a guarantee it will stay fixed for the whole draw period.
What happens when the repayment period starts?
Once the draw period ends, you can no longer borrow against the line, and the repayment period begins. Your payment converts to a fully amortizing principal-and-interest payment, calculated to pay off whatever balance you carried into repayment over the remaining term (commonly 10–20 years). Because this payment now includes principal, it is typically noticeably higher than the interest-only draw-period payment on the same balance.
Why does my payment jump when repayment begins?
The jump happens because the draw-period payment only ever covered interest — none of it reduced the balance. When repayment starts, the same balance now has to be paid off in full within the repayment term, so each payment must include a principal portion on top of interest. The larger the balance you carry into repayment, the shorter the repayment term, or the higher the rate, the bigger that jump will be. Some homeowners reduce the jump by paying down principal voluntarily during the draw period.
| Home value | $400,000 |
|---|---|
| Current mortgage balance | $220,000 |
| CLTV cap | 85% |
| Available credit line | $120,000 |
| Amount drawn | $50,000 |
| Draw period payment (interest-only) | $385/mo |
| Repayment period payment (20-yr amortization) | $458/mo |
Example only, using the calculator's default starting values above — enter your own numbers in the calculator to get your estimate. Actual available credit, rate, and required payment are set by your lender and can differ from this example.
Sources
- Consumer Financial Protection Bureau — general guidance on home equity lines of credit, draw periods, and repayment periods.
- Internal Revenue Service — Publication 936, Home Mortgage Interest Deduction (for questions about whether HELOC interest is deductible in your situation).
What this calculator is not
This calculator produces an estimate only, using the numbers you enter and standard interest-only / amortization formulas. It is not a loan offer, a rate lock, a credit decision, or a guarantee of the CLTV cap, rate, or terms any specific lender will actually offer you. Actual HELOC terms depend on your credit profile, property, lender, and market conditions at the time you apply, and variable rates can change the payment amounts shown here over time.
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Disclosure: This is general information, not advice about your specific situation.