maratoolCredit Card Interest Calculator
Enter balance, APR, and your monthly payment to see payoff time and total interest — next to what minimum payments would really cost.
Your payment
Minimum payments only
What is Credit Card Interest?
The Credit Card Interest Calculator simulates your balance month by month at your card’s APR. It answers two questions at once: how long your own monthly payment takes to clear the debt, and what happens if you only ever pay the minimum (interest plus 1% of the balance, the standard issuer formula). The gap between the two — often thousands of dollars and a decade or more — is the number card issuers hope you never compute.
How to use
- Enter your current card balance and APR from your statement.
- Add the monthly payment you can afford.
- Compare your plan against minimum payments — payoff time, interest, and savings update instantly.
Frequently asked questions
How is credit card interest calculated?
Card issuers divide your APR by 12 and charge that rate on the carried balance each month. A $5,000 balance at 24% APR accrues about $100 in interest per month.
Why do minimum payments take so long?
The typical minimum is interest plus 1% of the balance, so it shrinks as the balance shrinks. Most of each payment goes to interest, stretching payoff to decades.
What minimum payment does this calculator assume?
Monthly interest plus 1% of the balance, with a $25 floor — the most common issuer formula. Your card agreement states the exact rule.
Is my data sent to a server?
No. All calculations happen in your browser.
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