About Card Payoff Math
At typical card APRs in the twenties, a balance is a fire: $5,000 at 22% generates about $92 of interest in month one alone, and payments barely above that tread water for years. The minimum payment is engineered to be affordable, not to free you — seeing the actual timeline is what changes behavior.
Enter the balance and APR from your statement, then either your realistic monthly payment (to get the timeline and total interest) or your target months (to get the required payment). Both modes show interest as a percent of the balance — the number that makes the urgency concrete.
Tackling an installment loan instead? Use the Loan Repayment Calculator.
The Payoff Formula
Standard amortization, solved both ways (r = APR ÷ 1200):
Months = −log(1 − r·B ÷ P) ÷ log(1 + r) Payment = B·r ÷ (1 − (1 + r)⁻ᵐ) If P ≤ B·r: the balance never falls
Worked example: $5,000 at 22% with $200/month clears in 34 months with ~$1,800 interest (36% of the balance). To finish in 12 months instead: $467.97/month, cutting interest to $616. And $92/month? Never — it doesn't cover month one's interest, which the calculator flags rather than pretending.
Payment Size Changes Everything
$5,000 at 22% APR — the same debt at four payment levels (computed by this calculator):
| Monthly payment | Payoff time | Total interest | Interest vs balance |
|---|---|---|---|
| $125 | 73 months | $4,125 | 83% |
| $200 | 34 months | $1,800 | 36% |
| $300 | 21 months | $1,300 | 26% |
| $500 | 12 months | $1,000 | 20% |
Read the first row twice: near-minimum paying almost doubles the debt via interest. The jump from $125 to $200 saves $2,325 and three years — the steepest part of the payoff curve is right above the minimum.
Payoff Strategy That Works
Multiple cards: the avalanche (highest APR first) minimizes total interest — mathematically unbeatable; the snowball (smallest balance first) buys quick wins that keep people going. Both beat minimum-paying everything by years. Balance-transfer offers (0% intro APR) can genuinely help IF the transfer fee (typically 3–5%) beats the interest saved and the balance actually dies before the promo rate does.
While paying down: stop adding purchases to the payoff card (a card in payoff mode is frozen, not shopping), pay more than once a month if cash flow allows (interest accrues on average daily balance), and know that on-time minimums protect your credit while the strategy above kills the debt. If the numbers here say “decades,” nonprofit credit counseling and hardship programs exist precisely for that conversation.