Credit Card Interest Calculator

Use our free credit card interest calculator to estimate how much interest you will be charged on your credit card balance based on your APR, balance, and payment schedule.

Financial

Currency

Average Daily Balance

Annual Interest Rate (APR)

Days in Billing Cycle

days

Formula

Credit card interest is calculated using your daily balance and daily periodic rate. This calculator shows exactly how much interest you will be charged in a billing cycle.

Daily rate = APR / 365; Interest = Average daily balance x daily rate x days in cycle

Percentage: The percentage value you want to apply

Number: The original number or value

Result: The calculated result

How It Works

1Enter your average daily balance for the billing cycle.
2Enter your card's APR (Annual Percentage Rate).
3Enter the number of days in your billing cycle (typically 28-31).
4The calculator computes your daily periodic rate and total interest charge.

Examples

,000 average balance, 18% APR, 30-day cycle

1.Daily periodic rate = 18% / 365 = 0.0493%
2.Daily interest = ,000 x 0.000493 = .48
3.Cycle interest = .48 x 30 = .38

Result: .38

,000 average balance, 22% APR, 31-day cycle

1.Daily periodic rate = 22% / 365 = 0.0603%
2.Daily interest = ,000 x 0.000603 = .02
3.Cycle interest = .02 x 31 = .42

Result: .42

Frequently Asked Questions

Credit card companies use the daily balance method: they divide your APR by 365 to get a daily periodic rate, multiply by your average daily balance to get daily interest, then multiply by the number of days in the billing cycle.

The daily periodic rate is your APR divided by 365. For example, an 18% APR has a daily periodic rate of 0.0493% (18 / 365 = 0.0493%).

Pay your statement balance in full by the due date each month. Most cards offer a grace period between the statement date and due date where no interest accrues on new purchases.

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CalculateMe Team

Last updated: 2026-07-17

Examples

,000 average balance, 18% APR, 30-day cycle

1.Daily periodic rate = 18% / 365 = 0.0493%
2.Daily interest = ,000 x 0.000493 = .48
3.Cycle interest = .48 x 30 = .38

Result: .38

,000 average balance, 22% APR, 31-day cycle

1.Daily periodic rate = 22% / 365 = 0.0603%
2.Daily interest = ,000 x 0.000603 = .02
3.Cycle interest = .02 x 31 = .42

Result: .42

Frequently Asked Questions

The daily periodic rate is your APR divided by 365. For example, an 18% APR has a daily periodic rate of 0.0493% (18 / 365 = 0.0493%).

Pay your statement balance in full by the due date each month. Most cards offer a grace period between the statement date and due date where no interest accrues on new purchases.

Credit Card Interest Calculator

Formula

How It Works

Examples

,000 average balance, 18% APR, 30-day cycle

,000 average balance, 22% APR, 31-day cycle

Frequently Asked Questions

How is credit card interest calculated?

What is a daily periodic rate?

How can I avoid paying credit card interest?

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Credit Card Interest Calculator

Formula

How It Works

Examples

,000 average balance, 18% APR, 30-day cycle

,000 average balance, 22% APR, 31-day cycle

Frequently Asked Questions

How is credit card interest calculated?

What is a daily periodic rate?

How can I avoid paying credit card interest?

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