HELOC Draw & Repay Calculator
See both phases of a home-equity line of credit: the interest-only payment while you draw, and the amortizing payment once repayment begins.
How it works
Draw phase (interest-only) = balance × i · Repay phase = balance × i ÷ (1 − (1 + i)⁻ⁿ), i = APR ÷ 12, n = repayment months
A HELOC has two lives. During the draw period you can borrow and repay freely and the required payment is usually interest-only — cheap, but it pays down no principal. When the draw period ends the balance is recast into a fully amortizing loan over the repayment period, and the payment can jump sharply because principal is now included. This “payment shock” is the number to plan for before the draw window closes.
Worked example
On a $40,000 balance at 8.5%, the interest-only payment is 40,000 × 0.085 ÷ 12 ≈ $283/mo during the draw period. Amortized over a 15-year repayment period the payment rises to about $394/mo — a $111 jump — and total interest across both phases is roughly $64,900.
Frequently asked questions
Why does my HELOC payment jump so much later?
During the draw period most HELOCs only require interest, so the balance never falls. When repayment begins the full balance must amortize over the remaining years, adding principal to every payment — often a large, sudden increase.
Is a HELOC rate fixed?
Usually not. Most HELOCs carry a variable rate tied to the prime rate, so both the interest-only and repayment amounts move with the market. This calculator uses a single rate for illustration; run it at a higher rate to stress-test.
Can I pay down principal during the draw period?
Yes, and it is wise to. Paying more than the interest-only minimum shrinks the balance that gets recast, which softens the payment jump when repayment starts.
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Educational estimate, not financial, tax or lending advice. Confirm figures with your lender, agent or a qualified professional.