What is APR? How credit card interest is really calculated
APR stands for annual percentage rate: the yearly cost of borrowing on your card. But you aren't charged once a year. Interest is calculated much more often, and that is why the number on your statement can look different from a quick calculation.
Here is how it works, with one example: $2,000 at 24.99% APR.
From APR to what you actually pay
Most issuers turn the APR into a daily rate (APR ÷ 365) and charge it on your balance every day of the billing cycle. For 24.99% that is about 0.0685% a day.
- $2,000 for 30 days: 2,000 × 0.000685 × 30 ≈ $41.08.
- A simple monthly shortcut (APR ÷ 12 = 2.08% a month) gives $41.65.
The two are close, and our payoff examples use the monthly shortcut. Your statement is the authority: the exact figure depends on your daily balances and the days in the cycle.
Interest on interest
Because unpaid interest is added to the balance and then earns interest itself, the real yearly cost is higher than the APR. At 24.99% compounded monthly, the effective yearly rate is about 28%.
The grace period
If you pay your full statement balance by the due date, most cards charge no interest on new purchases. If you carry any balance past the due date, you generally lose the grace period and purchases start to accrue interest right away until you pay the card in full again.
Different APRs on the same card
- Purchase APR: the one most people mean.
- Cash advance APR: usually higher, and interest starts the same day, with no grace period.
- Penalty APR: can apply after a late payment, depending on the card agreement.
- Introductory APR: a low or 0% rate for a set time that then changes.
What to do with this
A high APR makes every month of a balance more expensive, so lowering the rate or the balance is what changes the result. See how a payoff works month by month, what the minimum costs or whether a balance transfer is worth it.
Frequently asked questions
What does APR mean on a credit card?
Annual percentage rate: the yearly cost of the interest on your balance, expressed as a percentage.
How is credit card interest calculated?
Most issuers divide the APR by 365 to get a daily rate and apply it to your balance each day, then add up the days in the billing cycle.
Is there a way to avoid paying interest?
Pay the full statement balance by the due date each month. Most cards then charge no interest on new purchases.
Why is the cash advance APR higher?
Issuers usually charge a higher rate on cash advances and start charging interest immediately, with no grace period.
See your interest in the calculator
Illustrative example, not financial advice. Figures use a simple monthly-interest model (APR ÷ 12 on the remaining balance). Your card issuer's statement may differ by a few dollars. Firchain AI is not a lender or a financial advisor.