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Credit Card Interest Calculator
Use this free credit card interest calculator to see how long it takes to pay off a card when you pay the same fixed amount every month. Enter your balance, your APR, and the monthly payment you plan to make, and it shows the months to pay off, the total interest, the total you will pay, and a month-by-month breakdown.
The same amount you pay every month until the card is clear.
Balance over time
Your balance falls slowly at first, then faster as less of each payment goes to interest.
How it works
A credit card charges interest every month on the balance you still owe. Your monthly payment is split in two: part pays that month's interest, and the rest — the principal — reduces the balance. Next month the interest is charged on the smaller balance, so it is a little lower, and a little more of your payment goes to principal. That is why the balance falls slowly at first and faster near the end, and why the chart beside the calculator curves downward instead of falling in a straight line.
Card balance is the amount you owe right now. APR is the annual percentage rate printed on your statement — the yearly cost of borrowing on that card. The calculator divides it by 12 to get the monthly rate. A 24% APR means 2% per month on the balance. Fixed monthly payment is the amount you choose to pay every month until the card is clear. It must be more than the first month's interest, or the balance will never fall. The optional extra monthly payment adds to your fixed payment, so you can see what paying a little more does to the payoff time and the total interest.
The calculator repeats that step month after month until the balance reaches zero, counting the months and adding up the interest. The last payment is usually smaller than the rest, because only a small balance is left. That month-by-month simulation is exact for a fixed APR with no new purchases — no guessing, no average. It also shows why the minimum payment is so costly: card issuers often set the minimum at 1% to 3% of the balance, which barely covers the interest. This page is for a fixed monthly payment you choose. If you want to see the payoff with minimum payments instead, use our Credit Card Minimum Payment Calculator, which shrinks the payment as the balance falls.
Three things change the result most. A higher APR means more of each payment is eaten by interest, so the payoff stretches out. A larger payment shortens it sharply, because every extra dollar goes straight to the balance. And new purchases undo progress, because they add to the balance and start earning interest themselves. The most useful way to use this tool is to try two or three payment amounts — your current payment, $50 more, and $100 more — and compare the total interest. The difference is often hundreds of dollars, which is a strong reason to raise the payment if you can.
Worked example
Suppose you owe $5,000 on a card with a 24% APR, and you pay a fixed $200 every month with no new purchases. Here is how the payoff works out, step by step.
Step 1: Find the monthly rate. 24% ÷ 12 = 2% per month, or 0.02.
Step 2: Work out the first month. Interest is $5,000 × 0.02 = $100.00, so of your $200 payment, $100 covers interest and $100 reduces the balance to $4,900.00.
Step 3: Repeat. In month 2 the interest is $4,900 × 0.02 = $98.00, so $102 of the payment goes to the balance, leaving $4,798.00. Each month the interest shrinks a little and the principal part grows.
Step 4: Keep going until the balance hits zero. The formula for the number of months is −ln(1 − balance × monthly rate ÷ payment) ÷ ln(1 + monthly rate), which is −ln(1 − 100 ÷ 200) ÷ ln(1.02) = 35.0 months — so 35 full $200 payments leave a tiny balance, and a 36th payment of $0.56 finishes it.
Enter the same numbers — $5,000 balance, 24% APR, $200 fixed payment — and the calculator shows exactly the same result: 36 months to pay off, $2,000.56 total interest, and $7,000.56 total paid. Add $50 a month and the same card clears in about 26 months with roughly $1,449 of interest — try it in the extra payment field.
FAQ
What happens if my monthly payment only covers the interest?
Then the balance never falls, and the card is never paid off. Each month the interest added equals the payment you make, so none of the payment reduces the balance. If your payment is even smaller than the monthly interest, the balance grows. This calculator warns you when your payment is too small to make progress.
Does this calculator use my card's APR as a fixed rate?
Yes. It assumes the APR you enter stays the same for the whole payoff period and that you make no new purchases on the card. In real life a variable APR can rise or fall, and new charges add to the balance, so treat the result as a plan based on today's rate rather than a promise.
Why is the total interest so high on a credit card?
Credit card APRs are much higher than most loan rates — often 20% or more — and interest is charged every month on the remaining balance. When the payment is small, most of it goes to interest and only a little reduces the balance, so the balance stays high for a long time and interest keeps piling up month after month.
Will paying a little extra each month really help?
Yes, more than most people expect. Every extra dollar goes straight to the balance, which shrinks the next month's interest, which leaves even more of the following payment for the balance. Try raising the payment in this calculator by $25 or $50 and watch the months and total interest fall.
Does this calculator include fees or late charges?
No. It counts interest only, based on the balance, APR, and fixed payment you enter. Annual fees, late fees, cash advance fees, and penalty APRs are not included, so your real cost can be higher if any of those apply.