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Credit card interest calculator
See exactly how much interest your card charges, using the daily periodic rate method most U.S. issuers use.
Credit card interest calculator
Runs in your browser. Nothing is stored.Usually 28 to 31.
- Daily periodic rate
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- Interest per day
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- Interest per year if the balance stays
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How card interest is calculated
Most issuers divide your APR by 365 to get a daily periodic rate, then apply it to your average daily balance for each day of the billing cycle:
daily rate = APR ÷ 365interest for the cycle = average daily balance × daily rate × days in cycleA few issuers use 360 days instead of 365, which makes the daily rate slightly higher. Your cardholder agreement says which one yours uses.
Example
With a $3,000 average daily balance and a 24% APR, the daily rate is 0.0658%. That's about $1.97 a day, or $59.18 over a 30-day cycle. If the balance stayed there all year, it would cost about $720.
How to pay less interest
- Pay in full by the due date. The grace period means purchases don't accrue interest when you pay the whole statement balance.
- Pay early in the cycle. Interest is based on the average daily balance, so paying sooner lowers it.
- Watch cash advances. They usually have a higher APR and no grace period.
For the full picture, read our guide to how credit card APR works.
Sources
Frequently asked questions
How is credit card interest calculated?
Most issuers divide your APR by 365 to get a daily rate, multiply it by your average daily balance, and multiply by the number of days in the billing cycle.
Do I pay interest if I pay my balance in full?
Usually not on purchases. If you pay the full statement balance by the due date, the grace period means no interest is charged. Cash advances are an exception.
What is a good credit card APR?
Anything well below the national average for accounts that pay interest, which has been above 20% in recent years according to Federal Reserve data.