HELOC Calculator
Estimate your Home Equity Line of Credit payments for both the interest-only draw period and the fully amortizing repayment period that follows.
Calculator verified • Last updated: August 2026
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Payment Schedule
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Balance Over Time
During the draw period your payment is interest-only, so the balance you owe doesn't move at all. Once the repayment period starts, each payment finally reduces the amount you borrowed, and the balance falls until it reaches zero.
Rate Sensitivity (Draw Period Payment)
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How HELOC Payments Are Calculated
A Home Equity Line of Credit works in two distinct phases, each with its own payment formula. During the draw period, most HELOCs only require interest-only payments: Once the repayment period begins, the drawn balance is paid off like any other fixed-rate installment loan:
D: the amount drawn against the credit line.
r: the monthly interest rate (the annual rate divided by 12).
n: the number of monthly payments in the repayment period (repayment years × 12).
Why the Payment Jumps So Much at Repayment
Because the draw-period payment only covers interest, the balance never shrinks during that phase — the full drawn amount is still owed on day one of repayment. Switching to an amortizing payment that must now pay off that entire balance over a fixed number of years produces a payment that's often two to three times higher than the interest-only payment, even with no change in rate.
Real HELOC Rates Are Variable — This Estimate Holds Them Fixed
Almost every HELOC charges a variable rate tied to an index like the prime rate, so your real interest-only payment during the draw period will move up and down as that index changes. This calculator uses one fixed rate across both phases purely to produce a clean estimate — treat the total-interest figure as a planning baseline, not a guarantee.
Worked Example
An 80,000-dollar credit limit with 40,000 dollars drawn at 8.5%, a 10-year draw period, and a 15-year repayment period: the draw-period payment is 40,000 × 8.5% ÷ 12, or about 283 dollars a month, all of it interest. Over 120 draw-period months that's roughly 34,000 dollars in interest with the balance still at 40,000 dollars. Repayment then amortizes that 40,000-dollar balance over 15 years (n = 180) at the same rate, giving a payment of about 394 dollars a month and roughly 30,901 dollars more in interest — a combined total of about 64,901 dollars in interest across both phases.
HELOC Terms You Should Know
Draw Period — the phase where you can borrow against the credit line (up to your limit) and typically only owe interest on what you've drawn.
Repayment Period — the phase after the draw period ends, when the outstanding balance amortizes to zero through fixed principal-and-interest payments.
Interest-Only Payment — a payment that covers only the interest accrued, leaving the principal balance unchanged.
Annual Fee — a yearly maintenance or membership fee some lenders charge just to keep the line of credit open, typically around 50-100 dollars a year. It's a separate periodic cost from your draw-period or repayment-period payment, not folded into the interest math above.
This calculator provides an estimate for planning purposes only, not a loan offer or financial advice. HELOC rates are typically variable and will differ from the fixed rate used in this estimate; confirm actual terms with your lender.
Frequently Asked Questions
Why does my HELOC payment jump once the draw period ends?
During the draw period you typically only pay interest on the amount drawn, so the payment stays low. Once the repayment period starts, the payment becomes a fully amortizing payment that pays off both principal and interest — usually significantly higher than the interest-only payment, even at the same rate.
Is a HELOC rate fixed or variable?
Almost always variable, tied to an index like the prime rate. This calculator holds the rate fixed across both the draw and repayment periods purely for estimation purposes — your real payments will move if the underlying rate changes.
Can I pay down principal during the draw period?
Yes — most HELOCs allow (and some require) principal payments during the draw period, and any principal you pay down can typically be redrawn. This calculator assumes the simplest case: interest-only payments through the full draw period, with the full drawn balance carried into repayment.
Does the annual fee change my HELOC payment?
No. The annual fee is a separate periodic account-maintenance cost, shown as a summary total over the full draw plus repayment period. It's not folded into the draw-period or repayment-period payment, which are still calculated from interest alone.
Is a HELOC the same as a home equity loan?
No. A HELOC is a revolving line of credit with a draw period and (usually) a variable rate, letting you borrow, repay, and re-borrow up to your limit. A home equity loan disburses one lump sum at a fixed rate, repaid on a fixed schedule from day one, with no revolving draw period. See the Home Equity Loan Calculator to model that lump-sum alternative instead.