How payoff time is calculated
A credit card charges interest each month on the remaining balance, so the formula for the number of months to clear it is n = −ln(1 − r·balance ÷ payment) ÷ ln(1 + r), where r is the monthly interest rate (APR ÷ 12 ÷ 100). We round up, because the final payment is usually a partial month. The catch: if your payment is less than or equal to the monthly interest charge (r × balance), the balance grows instead of shrinking and the card can never be paid off. Unlike a fixed installment debt priced by the loan calculator, a card balance shrinks only as fast as you pay it.
How to use this calculator
Enter your current balance, the card's APR, and the fixed monthly payment you intend to make. The tool returns the number of months to reach a zero balance, the total you will pay, and the interest cost. Paying more than the minimum dramatically shortens the timeline. If you are weighing a consolidation loan instead, compare it with the debt-to-income calculator.
Worked example
With a $5,000 balance at 18% APR paying $200 a month, the monthly rate is 0.015. It takes about 32 months to clear the debt, and you pay roughly $1,312 in interest. Raising the payment shortens it sharply:
| Monthly payment | Months | Interest paid |
|---|---|---|
| $150 | 47 | $2,005 |
| $200 | 32 | $1,312 |
| $300 | 20 | $786 |
| $500 | 11 | $432 |
These figures are an estimate for general information only and are not financial advice; consult a qualified professional before making money decisions. Seeing how a fixed-payment schedule compares is easy with the amortization calculator.
Frequently asked questions
- How long to pay off $5,000 at 18% APR?
- Paying $200 a month, it takes about 32 months to clear a $5,000 balance at 18% APR, costing roughly $1,312 in interest.
- What does 'payment too low to ever pay off' mean?
- It means your monthly payment is equal to or less than the interest charged that month, so the balance never decreases. You must pay more than the monthly interest.
- Does paying more than the minimum help?
- Hugely. Because interest compounds on the remaining balance, every extra dollar cuts both the payoff time and the total interest, often by months and hundreds of dollars.
- Is the interest figure exact?
- It is an estimate assuming a fixed APR, fixed payment, and no new charges. Real cards may change rates, add fees, or apply different minimum payment rules.
- What happens if I keep spending on the card?
- New purchases reset the math entirely, because interest is charged on the higher balance and your fixed payment then covers less principal. Either stop using the card, or add the expected new spending to the balance and run the numbers again.