Why credit card debt behaves differently
A card has no fixed term. A mortgage or car loan has a payment calculated to clear it by a set date; a card leaves the pace entirely to you, and the minimum is deliberately set low. Interest is charged on the balance each month, so a payment only reduces what you owe by the amount left after that month's interest is covered.
That single fact explains everything else. On a $4,200 balance at 22.9%, the first month's interest is about $80. A $100 payment moves the needle by $20. A $150 payment moves it by $70 — three and a half times as much, for 50% more money.
The minimum payment trap
Minimums are typically a small percentage of the balance, with a floor of around $25. Because the percentage is applied to a falling balance, the payment falls too — so the debt shrinks ever more slowly, and payoff stretches out for decades. Switch to Minimum only above to see it on your own numbers.
The definition varies by issuer: some charge a flat percentage of the balance, others charge a percentage plus that month's interest and fees, which pays off considerably faster. Check your statement and adjust the percentage and floor above to match.
What actually changes the outcome
- Fix the payment, don't follow the minimum. Paying the same amount every month, even a modest one, converts an open-ended debt into one with an end date. This is the single biggest change available to most people.
- New spending resets progress. These projections assume nothing further is charged to the card.
- A 0% balance transfer can beat any payment plan. Set the APR above to 0 to model the promotional window, then remember to check the transfer fee and what the rate reverts to afterwards.
- Rate matters less than payment. Try it: raising the payment usually shortens payoff more than shaving a few points off the APR.
If the payment never clears the balance
If what you can pay is less than the monthly interest, the balance grows no matter how long you keep paying, and this calculator says so rather than showing a date. That is not a budgeting problem to solve with a spreadsheet — it is the point to seek a lower rate, a consolidation loan, or free help from a non-profit debt charity.