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Credit Card Interest Calculator

Calculate how much you'll be charged on your credit card . Understand the real cost of carrying a balance and make informed decisions about your .
Enter your outstanding balance, your card's annual interest rate (APR), and the number of days in your billing cycle. After inputting these values, the calculator estimates the interest charged for one billing cycle if you carry that balance.
$
%
days
You will pay
$
in interest this billing cycle if you carry this balance.

How Credit Card Interest Is Calculated

How This Calculator Works

Enter your credit card's current , its , and how many days are in your . The calculator converts the APR to a daily periodic rate (APR ÷ 365), applies it to the balance every day of the cycle with daily compounding, and adds up the interest. It assumes no new purchases or payments during the cycle and that no grace period applies.

What's Included in the Calculation

  • Daily periodic rate (APR ÷ 365)
  • Daily over the billing cycle
  • A constant balance (no purchases or payments during the cycle)

Important Considerations

  • If you pay your statement balance in full by the due date, a grace period usually means no interest is charged on purchases
  • Issuers can calculate slightly differently (for example a 360-day year, or rounding per day)
  • Paying only the leaves a balance that keeps accruing interest
  • Interest rates are assumed to remain constant

Key Terms & Definitions

Current Balance

The total amount you currently owe on your credit card, including any unpaid purchases and previously accumulated interest. Issuers usually calculate interest on your average daily balance rather than the statement balance.

Monthly Payment

The amount you pay each month toward your credit card balance. Making larger payments reduces the total interest you'll pay and helps you become debt-free faster.

Compound Interest

Interest calculated on both the initial principal and the accumulated interest from previous periods. This means you're paying interest on interest, which can make debt grow faster than simple interest.

Annual Percentage Rate (APR)

The yearly interest rate charged on credit card balances. While APR is quoted as an annual rate, credit card companies use it to calculate interest charges on a daily basis.

Billing Cycle

The period between billing statements, typically around 30 days. This is the timeframe used to calculate your interest charges and determine payment due dates.

Finance Charges

The dollar cost of credit for a billing cycle: mainly interest on purchases, balance transfers and cash advances, plus certain credit-related fees such as cash-advance or balance-transfer fees. Late fees and annual fees are generally not finance charges.

Minimum Payment

The smallest amount you must pay each month to keep your account in good standing. While this amount is lower, paying only the minimum will result in much more interest paid over time and a longer payoff period.