HELOC Amortization Schedule Calculator
Generate a month-by-month HELOC payment schedule across both phases — interest-only draw period and full principal+interest repayment period — using 2026 prime-based variable rates. Free, private, runs in your browser.
| Period | Payment | Interest | Principal | Balance |
|---|
How a HELOC Amortization Schedule Works
A Home Equity Line of Credit (HELOC) has two distinct phases that produce very different payment amounts. The draw period typically lasts 10 years and allows interest-only payments — the borrower pays just the monthly interest on the outstanding balance, never reducing principal. The repayment period follows for 15-20 years and requires fully amortizing principal + interest payments to pay the balance to zero. The shift between phases — known as "payment shock" — can roughly double monthly payments overnight (source: CFPB).
2026 rate environment: HELOC rates are typically tied to the Wall Street Journal Prime Rate plus a margin (Prime + 0.5% to Prime + 3%). With Prime at approximately 7.5% in early 2026, average HELOC rates run 8% to 10.5%. Most HELOCs are variable-rate, meaning monthly payments can change every billing cycle as Prime moves.
Draw Period — Interest-Only Math
Monthly interest-only payment = (Balance × APR) / 12. Example: $50,000 balance × 8.5% / 12 = $354/month. The balance does not decline unless you make extra principal payments voluntarily. This is intentional — HELOCs are designed for flexibility during the draw period — but it means payment shock is unavoidable when repayment starts unless the borrower paid down principal voluntarily during the draw years (source: Federal Reserve).
Many lenders allow re-draws during the draw period — paying down principal and then re-borrowing. This calculator assumes a static balance during the draw phase. If you actively use re-draws, the actual schedule will vary.
Repayment Period — P+I Math
The repayment monthly payment uses the standard amortization formula: P × [r(1+r)^n] / [(1+r)^n − 1] where r = monthly rate and n = number of months in repayment. For a $50,000 balance at 8.5% over 20 years, monthly P+I = $434, of which most early payments go to interest. Total interest paid across the full repayment period on this example: approximately $54,160 — meaning the borrower pays back about $104,160 on $50,000 borrowed. Adding extra principal each month dramatically shortens the payoff and reduces total interest.
Variable-Rate Risk
Because most HELOCs are variable-rate, the monthly payment shown by this calculator is a snapshot at the entered rate. If Prime rises 1% during the draw period, your interest-only payment rises immediately — on a $50,000 balance, by about $42/month. During repayment, a rising rate extends the effective payoff timeline if your scheduled payment is fixed, or raises the monthly payment if payments are recalculated. The CFPB recommends modeling at +2% to +3% above the current rate to stress-test HELOC affordability.
HELOC vs Cash-Out Refinance vs Home Equity Loan
HELOC = revolving credit line, variable rate, 2-phase payment structure (draw + repay), best for ongoing or unknown spending needs. Cash-out refinance = lump sum, fixed rate, replaces existing mortgage entirely, best when current mortgage rate is high. Home equity loan = lump sum, fixed rate, second mortgage on top of existing first mortgage, best for known one-time expenses with stable rates. Use this calculator alongside our HELOC vs cash-out refinance comparison to pick the cheaper option for your situation.
Last updated April 2026. Estimates only — verify your actual lender's terms, prime rate, and margin. Sources: Consumer Financial Protection Bureau, Federal Reserve, Freddie Mac.