HELOC Payoff Calculator: Draw + Repayment Math

Your HELOC has two clocks

A HELOC behaves like two products glued together. There is a draw period, during which you can borrow up to your limit and the monthly payment is often interest-only on whatever you've drawn. There is a repayment period that follows, during which drawing usually stops and the balance amortizes over a fixed term — like a regular loan. The payment can change meaningfully between the two phases, even if your balance is similar.

The calculator above models the repayment phase. If you're still in the draw period, the most useful way to use it is forward-looking — enter the balance you expect to carry when repayment starts, and read off the payment that will begin then.

Clock 1

Draw period

Often around 10 years — check your agreement

Borrowing. You can usually draw up to your limit as needed.
Payment. Often interest-only or a low minimum on the drawn balance.
Rate. Typically variable — the payment can change between statements.
Balance behavior.Interest-only payments don't reduce the principal.
Lever. Extra principal here lowers the balance that has to amortize later.

Clock 2

Repayment period

Often 10–20 years — check your agreement

Borrowing. Drawing usually stops at the start of repayment.
Payment. The balance amortizes over the repayment term, so the payment can step up.
Rate. Often still variable — re-running the payment math after a rate move is normal.
Balance behavior. Each payment now includes principal as well as interest.
Lever. Extra payments shorten the payoff and cut total interest.

HELOC structures vary. Some don't separate the two phases the way described above, and some allow renewal at the end of the draw period. Your HELOC agreement controls — read it or ask your lender before relying on any planning estimate.

A worked example — $45,000 balance, draw period ending in 18 months

A homeowner has a $45,000 HELOC balance, a variable rate near 9%, and is still in the draw period. Their current payment is interest-only — roughly $337.50 a month at this balance and rate ($45,000 × 9% ÷ 12). The draw period ends in 18 months, after which the balance amortizes over a 20-year repayment term.

Plug $45,000, 9%, and 240 months into the calculator above. The monthly payment it shows is what the amortizing payment may be once the draw period ends — meaningfully higher than the interest-only payment the homeowner is used to. That gap is the payment-shock the next section describes.

Now suppose the homeowner adds $300 a month in extra principal during the remaining 18 months of draw. Servicers can apply payments differently — most will cover accrued interest and any fees first, with the rest reducing principal — so the extra may reduce the balance, but not by the full $300 in every cycle. Read your statement (or call the lender) to confirm how extras are applied. To the extent the paydown lands on principal, it lowers the balance entering repayment, which lowers the required payment and the total interest paid. Plug the reduced balance into the calculator to see the after-paydown amortizing payment.

Numbers are a planning estimate. Variable-rate moves between now and the start of repayment, billing-cycle timing, and the specific terms in your HELOC agreement can all shift the result.

Where HELOC borrowers get surprised

The minimum payment may be interest-only.A low minimum doesn't mean the loan is shrinking. Interest-only payments cover the interest accrued in the cycle and leave the principal where it was.
The payment can step up when the draw period ends. Switching from interest-only to amortizing repayment can raise the required monthly payment, even when the balance is roughly the same. The change is mechanical, not punitive.
A variable rate can raise the payment in either phase. The rate is usually a published index plus a margin set at origination. Index moves can change the payment in the draw period as well as in repayment.
Paying interest-only doesn't reduce the balance. If your goal is to reach a lower starting balance before repayment begins, the extra has to go above the interest-only minimum and land on principal. Check your statement to confirm how extras are applied.
Consolidating credit cards into a HELOC only works if the cards stay paid down. If the card balances come back, the HELOC has added secured debt to your home without removing the unsecured debt the cards represent.
The HELOC is secured by the home. Falling far behind on payments can put the home at risk through foreclosure proceedings. Treat any planning estimate as a starting point for a conversation with your lender, not the final word.
Interest deductibility depends on how you used the funds. Under current IRS rules, HELOC interest may be deductible only when the funds were used to buy, build, or substantially improve the home that secures the HELOC, and other limits (overall secured-debt cap, itemizing requirement) apply. Rules can change — verify with a tax professional before assuming a deduction.

Call your lender before relying on the number if…

A planning estimate is a starting point. For any of the situations below, the right next step is a phone call to the number on your statement — not a calculator.

The draw period ends within the next 12 months — or within 24 months and your statement doesn't show the repayment-period term or payment basis.
Your statement language mentions interest-only or minimum-only payments.
The rate is variable and recently changed.
You're weighing refinancing, selling, or consolidating other debts into the HELOC.
The payment will recast or transition to amortization soon.
You aren't sure whether your extra payments reduce principal immediately or sit as a credit.

Frequently asked questions

Does this calculator work during the HELOC draw period?

It models the repayment phase — the part of the loan after the draw period ends and the balance amortizes over a fixed term. If you're still in the draw period and want to see what your future payment may look like, enter your current balance and the repayment-period length your agreement specifies. Compare that figure to what you're paying today. Many HELOC agreements differ; your agreement controls.

Can I pay off a HELOC during the draw period?

Most agreements allow you to pay the balance to zero at any time. Some HELOCs charge a small early-closure fee if you close the line within the first 2–3 years (often around $300–$500). Paying to zero without closing the line usually avoids the fee and keeps the credit available. Check your HELOC agreement for the specific terms.

Will paying off my HELOC hurt my credit score?

It usually doesn't. HELOCs typically report as revolving credit, so paying down the balance can improve your credit utilization. Closing the line removes the available credit and may briefly lower the score, depending on the rest of your credit profile. Effects vary by reporting agency and individual situation.

How is HELOC interest calculated?

Most HELOCs accrue interest daily on the outstanding balance during the billing cycle, at a variable rate equal to a published index plus a margin set when the line opened. A payment reduces the balance that interest accrues on from then forward. Read your billing statement for the exact day-count and accrual rules your lender uses.

What I'd do next

Home equity loan payoff calculator
If you wanted a fixed-rate, fixed-payment second mortgage instead of a revolving line, the home equity loan page runs the same math without the draw-vs-repayment split.
Mortgage payoff calculator
For the primary mortgage on the same home — how extra payments shrink the schedule and how much interest the extras save.
Refinance calculator
If you're considering rolling the HELOC into a new first mortgage, the refi calculator shows the new payment and break-even on closing costs.

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Calculator and notes maintained by James L. Wu. The math here is the standard amortization formula every U.S. lender uses; HELOC-specific framing comes from CFPB consumer-finance guidance and the published terms in real HELOC agreements. Not financial, legal, or tax advice — confirm specifics against your HELOC agreement and a qualified professional. See methodology for the formulas and assumptions and the editorial policy for sourcing. Last refreshed May 2026.