Credit Card Interest Calculator
See exactly how much interest your credit card balance is costing you per day, month, and year.
Monthly Interest Charge
$0
📐 Formula
Monthly Interest = Balance × (APR ÷ 12). Daily Interest = Balance × (APR ÷ 365). Daily Periodic Rate = APR ÷ 365
Frequently Asked Questions
Credit card interest accrues daily using the Daily Periodic Rate (DPR = APR ÷ 365). Each day, interest is added to your average daily balance. This is why carrying a balance from month to month is so costly.
APRs below 15% are good. Most rewards cards range from 19–28% APR. If you pay your balance in full each month, the APR doesn't matter — you pay zero interest. The APR only applies to carried balances.
Pay your statement balance in full by the due date every month. Most cards have a grace period (21–25 days) where no interest accrues if you pay in full. Partial payments result in interest on the entire balance.