HELOC Payment Calculator
Estimate your available home-equity line, the low interest-only draw-period payment and the higher fully-amortizing repayment payment.
How it works
Available line = value × max CLTV% − mortgage balance · Interest-only payment = balance × rate ÷ 12 · Repayment payment = amortized payment on the balance over the repayment period
A HELOC is a revolving credit line secured by your home equity, with two phases. During the draw period you can borrow and repay freely and typically owe interest only, which keeps payments low but reduces no principal. When the draw period ends, the outstanding balance converts to a fully amortizing loan over the repayment period, so the payment jumps to cover principal too. Because HELOC rates are usually variable, both the interest-only and the repayment payment can move as rates change.
Worked example
On a $500,000 home with a $250,000 mortgage and an 85% CLTV cap, the lender allows total borrowing of $425,000, leaving about $175,000 available. Drawing $50,000 at 8.5% costs 50,000 × 0.085 ÷ 12 = about $354 a month interest-only; once it amortizes over 20 years the payment rises to about $434.
Frequently asked questions
How much can I borrow with a HELOC?
Lenders cap your combined loans — first mortgage plus HELOC — at a percentage of your home’s value, commonly 80% to 90%. Multiply the value by that cap, subtract your mortgage balance, and the remainder is roughly your available line, subject to credit and income checks.
Why does my HELOC payment go up later?
During the draw period many HELOCs let you pay interest only. When that period ends, the balance amortizes over the repayment term, so principal is added to each payment. Combined with a variable rate, the payment can rise noticeably — plan for the repayment-phase amount, not just the low draw-period figure.
Is a HELOC rate fixed or variable?
Most HELOCs carry a variable rate tied to the prime rate, so your payment changes when rates move. Some lenders offer a fixed-rate lock on part of the balance. Because of this variability, stress-test the payment at a higher rate before drawing a large amount.
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This is an educational estimate, not financial advice. Lenders use their own rounding, fees, mortgage-insurance rules and credit terms — confirm exact figures with your lender or a licensed advisor.