Credit Card Interest Calculator

See the daily and monthly interest accruing on your credit card balance.

How it works

Daily periodic rate = APR ÷ 365. Multiply by your balance and the days in the cycle to estimate interest charged.

Frequently asked questions

How is credit-card interest calculated?

Issuers use average daily balance × daily periodic rate × days in cycle. Daily periodic rate = APR ÷ 365.

Why is it sometimes higher than I expect?

Cash advances and balance transfers often have their own APR and start accruing immediately with no grace period.

How do I avoid card interest entirely?

Pay the statement balance in full by the due date. No interest is charged on purchases when you do.

What's a grace period?

The interest-free window (typically 21–25 days) between statement close and due date — only available if you carried no balance.

Does interest compound?

Yes — most cards capitalize interest into the balance, so unpaid interest itself accrues interest.

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