How credit card interest works
A credit card is revolving debt, not an instalment loan: there is no fixed term, and the required payment moves with the balance. Interest is charged monthly on what you still owe.
That second rule is why minimum payments are a trap. The interest is always covered, but only about 1% of the balance goes to principal, and as the balance falls the payment falls with it. A fixed payment keeps the amount constant while the interest portion shrinks, and the principal portion accelerates.
Worked example: $6,000 at 22.99% APR
The first month accrues $6,000 × 22.99% ÷ 12 = $115 in interest. The minimum payment starts at $174.95, of which only $60.00 touches the balance. Carried to the end, the minimum takes 20 years 10 months and costs $10,405 in interest — you repay $16,405 on a $6,000 debt.
What a fixed payment does instead
| Monthly payment | Time to clear | Total interest | Saved vs minimum |
|---|---|---|---|
| Minimum (from $174.95) | 20 years 10 months | $10,405 | — |
| $150 | 6 years 5 months | $5,492 | $4,913 |
| $200 | 3 years 10 months | $3,012 | $7,393 |
| $300 | 2 years 2 months | $1,639 | $8,766 |
| $500 | 1 year 2 months | $884 | $9,521 |
On $6,000 at 22.99% APR, assuming no new spending on the card.
Frequently asked questions
How long does it take to pay off $6,000 on a credit card?
Paying only the minimum at 22.99% APR takes 20 years 10 months and costs $10,405 in interest. Paying a fixed $300 a month clears it in 2 years 2 months for $1,639 — a saving of $8,766.
Why does the minimum payment take so long?
Because it falls as the balance falls. The minimum is usually the month's interest plus about 1% of the balance, so as you pay down the card the required payment shrinks with it and the principal is always being repaid at the slowest permitted rate. A fixed payment does the opposite: as interest falls, more of the same payment attacks the principal.
What happens if my payment is less than the interest?
The balance grows even though you are paying. On $6,000 at 22.99%, the first month alone accrues $115 in interest, so any payment below that goes backwards. This calculator says so plainly rather than showing an impossible payoff date.
Does a balance transfer help?
It can. Moving a balance to a 0% introductory rate stops interest accruing for the promotional period, so every dollar goes to principal — but transfer fees of 3-5% apply, and the rate reverts afterwards. Compare the fee against the interest you would otherwise pay over the same window.
Related tools
- Amortization schedule — how a fixed-term loan differs from revolving debt
- Paycheck calculator — what your take-home pay leaves for repayments
- Auto loan calculator — the same interest arithmetic over a fixed term