ConverterHub

Debt Payoff Calculator

See how long it takes to pay off a debt.

How it is calculated

The monthly rate is r = APR ÷ 100 ÷ 12. With a fixed payment P and balance B, the number of months is n = −ln(1 − B·r ÷ P) ÷ ln(1 + r), rounded up to a whole month. At 0% APR it is simply B ÷ P. If the payment is no more than the first month's interest (P ≤ B·r) the balance never shrinks and the tool returns nothing. Total paid is shown as P × months and interest as that total minus B, so the final payment is counted in full even though it is usually smaller. No new purchases, fees or changing rates are assumed.

Worked example

Balance 5,000, APR 18%, payment 200 a month. Monthly rate: 18 ÷ 100 ÷ 12 = 0.015. First-month interest is 75, so 200 does cover it. Then n = −ln(1 − 75 ÷ 200) ÷ ln(1.015) = 0.47 ÷ 0.014889 ≈ 31.6, rounded up to 32 months. Total at 200 per month: 6,400.00; interest: 6,400 − 5,000 = 1,400.00. The result is 32 months.

Try this example →

Common mistakes

  • Entering the monthly rate instead of the annual one. The field expects APR, such as 18, and divides by 12 itself.
  • Choosing a payment that barely exceeds the monthly interest. The payoff is then extremely long, and at or below the interest the tool returns no result at all.
  • Treating the interest figure as exact. It assumes 32 full payments, while the last one is usually smaller, so real interest is a little lower.
  • Including new purchases or planning to skip months. The model assumes a fixed payment on a balance that gets no new charges.

About this calculator

This calculator works backward from an amortization schedule: given a starting balance, a fixed monthly payment, and an annual percentage rate (APR), it computes how many months it takes to bring the balance to zero, applying interest each month before the payment reduces principal. It also totals the interest paid over the payoff period, showing how much of each payment goes to interest versus principal.

This is the exact math behind credit card minimum-payment traps and personal loan payoff plans — a card charging 22% APR with only minimum payments can take years longer and cost far more in interest than a fixed, higher payment would.

People building a debt-free plan for credit cards, personal loans, or store cards use this to compare payment strategies, financial counselors illustrating the cost of minimum payments to clients, and anyone deciding whether to throw extra money at a balance all rely on this calculation to see the real payoff timeline.

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