Debt Payoff Calculator
Enter your balance, interest rate and a fixed monthly payment to see how many months it takes to become debt-free and how much interest you will pay.
Last updated: June 20, 2026 · Fact-checked by TG we-Calculate Editorial Team%
2 years 9 months
- 1
Monthly interest rate
i = 19.99% ÷ 12 ÷ 100 = 0.016658 - 2
First month's interest
5,000 × 0.016658 = 83.29 - 3
Exact payoff months
−ln(1 − 5,000 × 0.016658 ÷ 200) ÷ ln(1 + 0.016658) = 32.6Rounded up to the nearest whole month. - 4
Months to pay off
⌈32.6⌉ = 33
How long will it take to pay off my debt?
Divide your APR by 12 to get the monthly rate, then apply the amortization formula months = −ln(1 − balance×rate ÷ payment) ÷ ln(1 + rate). Round up to a whole month. If your payment is smaller than the first month's interest, the balance never clears and you must pay more.
Formula
How this is calculated
Three inputs drive the result. The current balance (B) is what you owe today. The annual interest rate (APR) is converted to a monthly rate i by dividing by 12 and by 100 — so a 19.99% APR becomes roughly 0.01666 per month. The fixed monthly payment (P) is the same amount you commit to paying every single month.
The calculator treats the loan as an amortising debt: each month interest of B·i is added to the balance, then your payment P is subtracted, leaving a smaller balance that accrues less interest next month. Because this repeats, the payoff time has a closed form — months = −ln(1 − B·i ÷ P) ÷ ln(1 + i) — which is rounded up to a whole month, then a month-by-month pass sums the actual interest so the smaller final payment is counted accurately. Total amount paid is simply balance plus total interest.
Key assumptions: a constant APR, no new charges, no fees, and a payment that never changes. If P is less than or equal to the first month's interest (B·i), the balance never shrinks and the debt is reported as never paid off.
Examples
| Input | Result |
|---|---|
| $5,000 balance, 19.99% APR, $200/month | 33 months (2 years 9 months), ~$1,521 interest |
| $10,000 balance, 6% APR, $300/month | 37 months (3 years 1 month), ~$967 interest |
| $2,000 balance, 0% APR, $250/month | 8 months, $0 interest |
About this calculator
The debt payoff calculator answers a simple question: if you keep paying a fixed amount every month, when will the balance reach zero? It uses the standard amortization formula, which accounts for interest accruing on the remaining balance each month.
The monthly interest rate is the annual APR divided by 12. Each month, interest is added to the balance and your payment is subtracted. The number of payments needed is found in closed form, then rounded up to a whole month, since the final payment is usually smaller than the rest.
A crucial check: if your monthly payment is less than or equal to the first month's interest, the balance never shrinks and the debt is never repaid. In that case you must increase the payment. Paying even a little more than the minimum can cut years and substantial interest off the payoff time.
Frequently asked questions
If your monthly payment is less than or equal to the interest charged in the first month (balance × monthly rate), the balance grows or stays flat instead of shrinking. Increase the payment so it exceeds the monthly interest.
Yes — because interest compounds on the remaining balance, even a small increase in your payment can shorten the payoff time by months or years and save a meaningful amount of interest.
It is a close estimate based on a fixed payment and constant APR. The figure accounts for the smaller final payment, but real accounts may vary with fees, changing rates or different billing-cycle conventions.
Also known as
Sources & references
TG we-Calculate Editorial Team. (2026). Debt Payoff Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/debt-payoff-calculator
TG we-Calculate Editorial Team. "Debt Payoff Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/debt-payoff-calculator.
TG we-Calculate Editorial Team, "Debt Payoff Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/debt-payoff-calculator
@misc{wecalculate_debt_payoff_calculator, title = {Debt Payoff Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/debt-payoff-calculator}}, year = {2026}, note = {TG we-Calculate} }
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