HELOC Payment Calculator
Estimate HELOC interest-only payments during the draw period, the amortizing payment after it, the payment jump, and how a rate increase changes them.
Interactive calculator · Method HELOC-PAYMENT-1.0 · Last reviewed: 2026-11-04
Calculate your scenario
Interest-only payment = drawn balance × annual rate ÷ 12 ÷ 100.
Your inputs
Default worked example. Edit the inputs to calculate your scenario.
Default worked example
Draw: $50,000.00 × 8.5% ÷ 12 = $354.17 a month; repayment over 240 months at 8.5% is $433.91, a jump of $79.74.
How to use the calculator
Enter the balance you expect to have drawn, the current rate, the draw and repayment lengths from your plan, and a rate increase you want to test. Use the table for one point lower through three points higher.
What the result means
A $50,000 balance at 8.5% costs $354.17 a month interest-only; when the 20-year repayment starts the payment becomes $433.91, and a 2-point rise would make it $499.19.
Formula and units
Interest-only payment = drawn balance × annual rate ÷ 12 ÷ 100. Repayment payment M = B × r ÷ (1 − (1 + r)^−n), with r = rate ÷ 12 ÷ 100 and n = repayment years × 12 (B ÷ n at 0%). The shocked payment uses rate + the increase you enter. Payment jump = repayment payment − interest-only payment. Total interest = interest-only payment × draw months + repayment payment × n − balance.
Worked examples
$50,000 drawn at 8.5%, 10-year draw and 20-year repayment: Drawn balance: 50000 USD; Current annual rate: 8.5 %; Draw period (interest-only): 10 years; Repayment period: 20 years; Rate increase to test at repayment (scenario): 2 percentage points.
Example result: Interest-only payment during draw: $354.17; Repayment payment at current rate: $433.91; Repayment payment at shocked rate: $499.19 at 10.5%; Payment jump at end of draw: +$79.74 (+$145.02 with the shock); Interest during draw period: $42,500.00; Total interest, draw + repayment: $96,638.79.
$120,000 at 9.25%, 5-year draw and 15-year repayment: Drawn balance: 120000 USD; Current annual rate: 9.25 %; Draw period (interest-only): 5 years; Repayment period: 15 years; Rate increase to test at repayment (scenario): 3 percentage points.
Example result: Interest-only payment during draw: $925.00; Repayment payment at current rate: $1,235.03; Repayment payment at shocked rate: $1,459.56 at 12.25%; Payment jump at end of draw: +$310.03 (+$534.56 with the shock); Interest during draw period: $55,500.00; Total interest, draw + repayment: $157,805.53.
Limitations and common mistakes
Assumes the drawn balance stays the same through the draw period (no new draws or extra payments) and a fixed rate within each scenario; real HELOC rates are usually variable and reset with an index, and some plans have minimum payments, fees or balloon terms that differ from this. The rate and the defaults are examples to replace with your plan’s terms; the rate increase is a scenario you choose, not a forecast. Not a product recommendation.
Budgeting on the interest-only payment. It pays no principal, so the payment rises when repayment begins even if the rate never changes.
Sources and assumptions
Method HELOC-PAYMENT-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.