Debt Payoff Calculator
See how long it takes to pay off a single debt and how extra payments save you money.
Last reviewed: June 2026Quick Answer
A debt payoff calculator shows how long until you're debt-free and how much interest you'll pay, based on your balance, interest rate, and monthly payment. Paying more than the minimum shortens the timeline and cuts total interest sharply. Enter your balance, rate, and payment above to see your payoff date, total interest, and how extra payments help.
How the Debt Payoff Calculator works
This calculator models one debt at a time. Enter the current balance, APR, required monthly payment, and any extra amount you plan to add each month. The calculator estimates the payoff month, total interest, total amount paid, and the time and interest saved by the extra payment. It also builds an amortization schedule so you can see how each payment is split between interest and principal.
The math is straightforward but easy to underestimate. Each month, the balance accrues interest based on APR divided by 12. Your payment covers that month's interest first, then the remainder reduces principal. The lower the principal gets, the less interest accrues in later months. Extra payments work because they push more money directly against principal earlier in the schedule.
Worked example
For a $10,000 balance at 20% APR with a $300 monthly payment, a large share of the early payments goes to interest. Adding even $50 or $100 per month can shorten the payoff timeline because it reduces the balance before future interest is calculated. Use the extra-payment field to compare a realistic baseline payment with an aggressive payoff plan.
When to use this page
- Credit cards: Estimate how long a balance takes to clear at the current APR and payment.
- Personal loans: Compare the scheduled payment with a higher self-imposed payment.
- Student or auto loans: Test whether extra principal payments materially shorten the term.
- Refinance decisions: Compare the current APR payoff path with a lower-rate offer, including fees separately.
Common mistakes
- Modeling several debts as one: Different APRs need separate calculations or a multi-debt snowball/avalanche tool.
- Ignoring payment changes: Promotional APRs, minimum-payment formulas, and late fees can change the real schedule.
- Paying less than monthly interest: If the payment is too small, the balance may grow rather than shrink.
- Forgetting emergency cash: Paying debt faster is useful, but leaving no cash buffer can force new borrowing after an unexpected bill.