Credit Card Interest Shock + Event Adder
Credit Card Payoff Calculator — What Minimum Payments Really Cost
What this calculator does
This tool shows the true cost of paying the minimum on one or more credit cards. Add each card's balance, APR, and minimum payment terms, then compare the combined payoff timeline with and without a one-time extra purchase, like an impulse buy or emergency expense.
The math, with a worked example
Minimum payment = max(balance × minimum %, floor amount). Each month interest = balance × APR ÷ 12. The tool loops payments until every card balance hits zero and totals combined months, interest, and the added cost of the extra purchase. With one card at $3,000, 24.99% APR, 3% minimum payment, and a $25 floor, the minimum payment starts around $90. Adding a $500 impulse purchase to that card stretches the combined payoff and adds hundreds in extra interest.
Why this matters
A minimum payment is engineered to keep the balance alive: most of the $90 goes to interest, the principal barely moves, and one impulse purchase stretches the timeline by months. The month-count and total-interest numbers are what the statement never adds up for you.
Methodology and transparency
Minimum payment = max(balance × minimum %, floor); each month interest = balance × APR ÷ 12; the loop runs until every card hits zero. The model assumes the minimum recalculates down as the balance falls — the exact mechanism that stretches payoff to decades — and assumes no new charges, so a card still in use will do worse than the projection. Your statement's own minimum-payment disclosure box is the cross-check. Everything runs in your browser; no data is sent or stored.
Last reviewed: 2026-08-08
Common questions
How is the minimum payment calculated?
It is the larger of the balance times your minimum percentage or the floor amount, usually $25–$35.
Why does minimum payment take so long?
Because most of the payment goes to interest, so the principal shrinks slowly and the term stretches for years.
How much does one extra purchase add in interest?
The calculator shows the extra months and combined interest caused by adding a one-time extra purchase to one card and paying only the minimum across all cards.
What counts as an extra purchase?
Any one-time charge you add to one of your balances: an impulse buy, a vacation, a car repair, or another unplanned expense.
Should I pay more than the minimum?
Yes. Even an extra $25–$50 per month can cut months or years off the payoff and save hundreds in interest. But before funding a payoff from retirement savings, price what the withdrawal actually leaves you: the penalty plus taxes can take nearly a third.
Can I add more than one card?
Yes. Click Add Another Card to enter as many cards as you need. The calculator totals the combined balance, months, and interest.