Credit Card Interest Calculator
See how long it takes to pay off a credit card balance and how much interest you'll pay.
This tool runs entirely in your browser. Your files are never uploaded to a server.
Assumes a fixed monthly payment, a constant APR, and no new purchases added to the balance; a real statement's minimum payment, fees and grace period can change the actual payoff time.
34
Months to pay off
1749.88
Total interest paid
What this calculator does
Simulates a revolving credit card balance paying a fixed amount each month, reporting how many months it takes to reach zero and the total interest paid along the way.
How to use it
Enter the current balance, the card's APR, and a fixed monthly payment you plan to make every month. Use one currency and keep the payment amount realistic for your budget.
Worked example
A 5,000 balance at 22% APR paid down with a fixed 200 monthly payment takes 34 months to reach zero, with about 1,749.88 in total interest paid. Automated tests verify this figure.
Formula and calculation order
Each month, interest = current balance × (APR ÷ 100 ÷ 12) is added to the balance, then the fixed payment is subtracted; the simulation stops once the balance reaches zero or a 600-month cap. If the payment does not exceed the very first month's interest, the balance can only grow, so the calculator reports this immediately as never paid off rather than simulating indefinitely.
Why a larger payment matters so much
Because interest compounds on whatever balance remains each month, a modest increase in the fixed payment reduces both the payoff time and the total interest more than proportionally — extra dollars paid early avoid interest that would otherwise accrue on them for every remaining month.
Assumptions and limits
The model assumes one constant APR, a payment made in full every month, and no new purchases, cash advances, fees or promotional-rate periods added to the balance. A real statement's minimum-payment formula, due dates, grace period and any balance-transfer terms can produce a different payoff time than this simplified simulation.
Scope, sources and privacy
This is an educational estimate, not financial or credit-counseling advice. The compounding mechanics were checked against Consumer Financial Protection Bureau credit card guidance. Reviewed September 2026. Calculation runs locally in the browser; Quiklio does not upload the entered values.
Frequently Asked Questions
- Why does the calculator warn me sometimes instead of showing a result?
- If your fixed monthly payment is less than or equal to the interest that accrues in the first month, the balance would grow forever — the calculator flags this instead of simulating an infinite payoff.
- Does making a larger payment really make a big difference?
- Yes — because interest compounds on the remaining balance every month, even a modest increase in your fixed payment can cut both the payoff time and total interest significantly.
- How is monthly interest calculated?
- It uses your APR divided by 12 as the monthly rate, applied to the current balance each month before your payment is subtracted.