How Credit Card Interest Works

Credit-card interest depends on the balance type, APR, payment timing, and the method described in your card agreement. A monthly calculator can show a useful simplified estimate, but it cannot reproduce every issuer's statement calculation.

Daily balance calculations Many card issuers calculate interest each day using a daily periodic rate and a daily or average daily balance. The daily rate may be based on APR divided by 360 or 365, depending on the issuer and account terms. The CFPB's explanation of daily periodic rates describes the basic mechanics.

Grace periods vary by account Some cards let you avoid interest on new purchases when you pay the full statement balance by the due date, but the rules depend on the agreement and whether you carried a balance. Do not assume a grace period applies to every balance type or in every billing cycle. Check your statement or ask the issuer how it applies to your account.

Payments and timing When interest accrues daily, the timing of payments can affect the balance used in the calculation. Payment allocation can also depend on the account terms and applicable rules. Continue to meet the required minimum and review the issuer's instructions before relying on a simplified schedule.

The MoneyPath Debt Payoff Planner uses monthly APR ÷ 12 estimates. It does not model daily balances, grace periods, fees, or promotional-rate rules.