HELOC Calculator
HELOC payment math. See your interest-only draw-period payment and the much higher amortizing payment that kicks in when the draw period ends.
Last reviewed: · Reviewed by the Money Scale editorial team · How we source our data
Power mode. Every input exposed, every assumption sourced, charts and shareables.
$50,000
10 years interest-only
20 years amortizing
Draw period
$302.50
interest-only / mo
Repayment period
$395.49
P+I / mo (amortizing)
Payment jump
$92.99/mo
1.3× higher
Draw interest paid
$36,300
Total interest (full life)
$81,218
📉 $302.50/mo draw
$50,000 HELOC @ 7.260% with a 10-year interest-only draw period.
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The HELOC Calculator models the two-phase structure of a Home Equity Line of Credit: an interest-only draw period (typically 10 years) then an amortizing repayment period (typically 20 years). When the draw period ends, the monthly payment usually DOUBLES — most HELOC users are caught off guard. This calculator shows both phases clearly so the payment shock isn't a surprise.
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How this calculator works
- Enter your HELOC balance during the draw period.
- Enter the current interest rate (HELOCs adjust monthly with prime — check your statement).
- Set the draw period length (10 years is most common) and repayment period (typically 20 years).
- Compare the two payment phases. Draw is interest-only and small; repayment is amortizing and much higher. Plan for the transition.
draw_payment = balance × (APR/12) repayment_payment = balance × [r(1+r)ⁿ / ((1+r)ⁿ − 1)]Two distinct formulas. During the draw period (~10 years), you pay only interest — the balance doesn't decline. When repayment starts, the full balance amortizes over the remaining term (typically 20 years), so the monthly payment is the standard amortization formula. The variable rate (tied to prime) means actual payments can move during the loan.
- balance
- Outstanding HELOC balance
- APR
- Annual percentage rate (variable, tied to prime)
- r
- Monthly rate (APR/12)
- n
- Number of payments in the repayment phase (years × 12)
Frequently asked questions
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