Debt Payoff Calculator
Find out how long a fixed monthly payment takes to pay off a balance.
Try an example
32.6
About this calculator
How This Debt Payoff Calculator Works
Enter a balance, an annual interest rate, and a fixed monthly payment, and the calculator returns how many months it'll take to pay off the debt, plus the total interest you'll pay along the way.
Worked Example
A $5,000 balance at 19.99% APR, paid down at $200/month, takes about 32.6 months (roughly 2 years 9 months) to pay off — with $1,520.62 in total interest, on top of the original $5,000.
The Formula
n = −ln(1 − Br/P) ÷ ln(1 + r), where B is the balance, r is the monthly interest rate (annual rate ÷ 12), and P is the monthly payment. This solves for the number of months n it takes a fixed payment to fully amortize a balance under compound interest — the same math behind a loan payment formula, run in reverse.
Why the Payment Must Exceed the First Month's Interest
If the monthly payment is less than or equal to the interest charged in the very first month, the balance never shrinks — every payment gets absorbed by interest and the debt technically never pays off. On the example above, the first month alone accrues $83.29 in interest, so any payment at or below that amount would leave the balance stuck or growing. This is a real trap with minimum credit card payments, which are sometimes set close to the interest-only threshold.
The Fastest Way to Cut the Total Interest
Increasing the monthly payment shortens the payoff time and reduces total interest — often disproportionately, since more of each extra dollar goes straight to principal rather than being consumed by interest on a larger balance for longer. Even a modest increase over the minimum payment can save meaningfully on interest paid.
Worked example
A $5,000 balance at 19.99% APR with $200/month payments clears in about 32.6 months (2.7 years) — roughly $6,524 total, including about $1,524 in interest.
Frequently asked questions
Why does the calculator say my payment is too low?
If your payment doesn't exceed the first month's interest charge, the balance never shrinks — it can even grow. You'll need to raise the payment above that interest amount for any payoff plan to work.
Does paying more each month really make a big difference?
Yes, often dramatically — on a credit-card-rate balance, doubling your payment can cut both the payoff time and total interest by more than half, since less of the balance sits around accruing interest.
Does this assume the interest rate stays fixed?
Yes — it assumes a constant APR and a fixed payment every month with no new charges added. A variable-rate card or new purchases would change the real payoff time.
Is this the same as a loan payment calculator?
It solves the opposite problem — a loan calculator finds the payment for a fixed term; this finds how long a fixed payment takes to clear the balance.