HELOC Payment Calculator

Q: What's the difference between a HELOC and a home equity loan?

A home equity loan gives you a lump sum upfront with a fixed rate and fixed payment from day one. A HELOC (home equity line of credit) works like a credit card secured by your home — you draw funds as needed during a draw period, typically paying interest-only, then repay the balance during a separate repayment period, usually at a variable rate.

Q: Why does my HELOC payment jump so much after the draw period?

During the draw period, most HELOCs only require interest payments, so your payment is small relative to the balance. Once the repayment period begins, you start paying down principal too, on a much shorter remaining timeline — which is why the payment often more than doubles even if the balance and rate haven't changed.

Q: Is HELOC interest still tax-deductible?

Only if the funds are used to buy, build, or substantially improve the home securing the loan, per current federal tax rules. Using a HELOC for other purposes, like debt consolidation or a car purchase, generally doesn't qualify for the mortgage interest deduction.

Q: Do HELOC rates change during the loan?

Most HELOCs have a variable rate tied to an index like the prime rate, so your payment can change during both the draw and repayment periods as rates move — this calculator assumes a fixed rate for simplicity.

Calculate your HELOC payment during both the interest-only draw period and the fully-amortizing repayment period — and see how much it jumps when draw ends.

Written by the Calculator Index team · Source: standard HELOC structure (interest-only draw period, amortizing repayment period) · Last reviewed September 2026

Draw period payment (interest-only)

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Repayment period payment

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Payment increase

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Total interest during draw

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Total interest during repayment

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How a HELOC's two phases work

Draw period payment = Balance × (Rate ÷ 12) — interest-only, principal untouched
Repayment period payment = Balance × r / (1 − (1 + r)⁻ⁿ) — a normal amortizing payment over the remaining term

A HELOC has two very different payment phases. During the draw period, you typically only pay interest on whatever you've borrowed — the balance doesn't go down on its own. When the draw period ends, you enter the repayment period: the outstanding balance is now amortized over a fixed term (often 10-20 years), which means you're paying both principal and interest — and on a shorter remaining timeline than the loan's total life, so the jump in payment can be significant.

Worked example — $50,000 balance, 8% APR, 10-year draw, 15-year repayment

Draw period payment (interest-only): $50,000 × (8% ÷ 12) = $333/month.

Repayment period payment (15-year amortization on the same $50,000): $478/month — a jump of about $145/month, or roughly 43% higher, once principal payments begin.

Why the payment jump surprises so many HELOC borrowers

Because the draw-period payment only covers interest, borrowers sometimes underestimate what their real monthly obligation will be once repayment starts — especially if they've continued drawing funds throughout the draw period, since the payment jump applies to whatever the final balance is, not the original credit line. Understanding both numbers upfront, not just the low draw-period payment, is the key to avoiding payment shock.

Common mistakes when estimating a HELOC payment

Budgeting around the draw-period payment long-term. That number is temporary — the repayment-period payment is the one that matters for long-term affordability.
Forgetting the rate is usually variable. This calculator assumes a fixed rate for simplicity; a real HELOC's rate — and therefore payment — can move with the market in both phases.
Confusing a HELOC with a home equity loan. A home equity loan is a lump sum with a fixed payment from day one; a HELOC has this draw-then-repay structure instead.

Frequently asked questions

What's the difference between a HELOC and a home equity loan?

A home equity loan is a fixed lump sum with a fixed payment from the start; a HELOC is a credit line with an interest-only draw period followed by an amortizing repayment period.

Why does my HELOC payment jump so much after the draw period?

Because you start paying principal too, on a shorter remaining timeline, once the draw period ends — the payment can jump substantially even with the same balance and rate.

Is HELOC interest still tax-deductible?

Only if the funds were used to buy, build, or substantially improve the home securing the loan, under current federal rules.

Do HELOC rates change during the loan?

Most HELOCs carry a variable rate, so payments can change during both phases — this calculator assumes a fixed rate for simplicity.

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Note: Simplified estimate assuming a fixed rate throughout both phases; actual HELOC rates are typically variable. Not financial or tax advice. Last reviewed: September 2026.