HELOC Payment Calculator before and after the draw period
Enter what you have drawn, the rate and the two phase lengths. You get the interest-only payment, the amortizing payment that replaces it, and the gap between them.
Interest Only Is Not Free
The draw payment covers interest and nothing else. Your balance is exactly the same after a decade of paying it.
Variable Rate
Most HELOCs float. Run the numbers again two or three points higher before you rely on the payment.
What is a HELOC payment?
At a Glance
A home equity line of credit runs in two phases. During the draw period you may borrow and repay freely, and the required payment is interest only. When the draw period ends the line closes to new borrowing and the repayment period begins, during which the whole balance must be cleared — so the payment becomes a full amortizing one.
The draw payment is the simpler of the two: it is just one month's interest on what you owe.
payment = balance × (annual rate ÷ 12)The repayment payment is the standard annuity formula, the same one behind every mortgage and car loan on this site.
M = P · i · (1 + i)ⁿ ÷ ((1 + i)ⁿ − 1)According to the Consumer Financial Protection Bureau, the end of the draw period is the moment borrowers are most often caught out, and Federal Reserve consumer guidelines make the same point.
The gap between them is the number worth planning around. On the default figures it is a modest 79.74 a month — but that is only because the repayment period is twice as long as the draw period. Shorten it and the jump gets much worse.
Start with the defaults: 50,000 drawn at 8.5 %, a ten-year draw period and a twenty-year repayment period.
Work out the monthly rate
8.5 % ÷ 12 = 0.7083 % a month.
The draw payment
50,000 × 0.7083 % = 354.17. Over ten years that is 42,500 in interest, and the balance is still 50,000.
The repayment payment
The annuity formula over 240 months gives 433.91, which adds another 54,138.79 of interest.
The jump
433.91 − 354.17 = 79.74 more a month, a 1.23× increase. Total interest across both phases: 96,638.79 — nearly twice what was borrowed.
Now shorten the repayment period
Keep 25,000 at 7 % but give it a ten-year draw and a ten-year repayment: 145.83 becomes 290.27. That is a 1.99× jump — the payment essentially doubles overnight.
That last case is the one that catches people. The shorter the repayment period relative to the draw period, the harder the step-up.
Judge the line by the repayment payment, not the draw payment. The draw payment is what you pay for the first decade; the repayment payment is what you have committed to. If the second number does not fit your budget, the line is too large regardless of how comfortable the first one feels.
Interest-only means the balance never moves. Ten years of the default payment costs 42,500 and leaves the debt untouched. That is not a flaw in the product — it is the product. It only makes sense if you are deliberately buying flexibility, or if you intend to repay principal voluntarily during the draw.
Paying principal during the draw period is usually allowed and almost always wise. Anything above the interest-only minimum comes straight off the balance and shrinks the eventual repayment payment.
A rising rate hits both phases. Because most HELOCs float, the draw payment moves with the index immediately and the repayment payment is set from whatever the rate is when amortization begins.
This is a planning estimate, not an offer. It has real limits.
It assumes a fixed rate. Almost no HELOC is fixed. The calculation treats your rate as constant for both phases, which is the right way to compare structures but the wrong way to predict the future. Run it again at several rates.
It assumes the balance is drawn up front and held. Real draws move month to month, and interest is charged on the daily balance. If you draw and repay repeatedly, your actual interest will be lower than the figure here — this is the worst case, deliberately.
It ignores fees. Annual fees, inactivity fees, appraisal and closing costs, and early-termination fees are all common on HELOCs and none are in the payment.
Some lenders require a balloon instead of amortization. A minority of lines end the draw period by demanding the balance in full. Check which structure yours has, because that changes everything.
Your home is the collateral. This is secured debt. Missing payments on a HELOC puts the property at risk in a way that missing a credit-card payment does not.
This calculator is provided for informational purposes and planning purposes only. It is not legal or tax advice. Consult a financial advisor or accountant, and verify the compliance and disclosure requirements that apply to your agreement, before drawing on a line secured by your home.
For a fixed-rate lump sum instead of a line, compare with the Home Equity Loan Calculator. To check how much a lender will release in the first place, the same page works out your borrowing ceiling. For the underlying amortization math, see the Loan Payment Calculator.