Credit Card Payoff Calculator

How the math works

This page starts from the cards most people carry: revolving balances with APRs in the teens or twenties. Enter each card's balance, APR, and minimum payment — or leave the minimum blank and let the calculator estimate it — plus the total amount you can put toward all cards each month. The preset ordering here is avalanche: after every card's minimum is covered, the remaining budget goes to the unpaid card with the highest APR first. Because a higher APR adds more interest per dollar of balance, directing the extra dollars there first is what produces the smallest total-interest figure for a fixed monthly budget. The results table shows that figure next to the payoff date, so the comparison is pure arithmetic.

Each simulated month follows the same steps. First, one month of interest is added to every unpaid card at balance × APR ÷ 12. Then minimums are paid to all cards, any per-card extra amounts are applied, and the leftover budget goes to the target card — cascading to the next card in priority order if the target is cleared. When a minimum is left blank, it is estimated as the largest of three values: 2% of the balance, one month's interest plus 1% of the balance, or $25. That mirrors common issuer formulas without being any single issuer's exact rule, so typing the minimum from your statement gives the more faithful result. A card with a $0 balance is treated as already paid and never targeted.

Four assumptions apply to every run. One, monthly compounding: interest accrues once per month at APR ÷ 12, before payments. (Some loans use a daily periodic rate, which would give slightly different numbers.) Two, the minimum-payment estimate described above, recomputed from the current balance each month. Three, the simulation stops at 600 months: a plan that has not cleared every balance by then is reported as not paid off within the simulation limit, with no extrapolation beyond it. Four, all math runs in full double precision with no per-month rounding; displayed dollars are rounded half-up to the nearest cent, and totals are summed from unrounded values before rounding.

If the question is how many months a single card takes, the how-long-to-pay-off calculator frames the same math around time. To see what paying only the estimated minimums costs across the whole schedule, the minimum-payment calculator puts that baseline front and center.