Credit Card Interest Calculator (Daily and Monthly Interest)
Enter the balance carried and the card’s APR to see what it costs.
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Credit Card Interest Calculator (Daily and Monthly Interest) by TheCalcTools
How the Credit Card Interest Calculator (Daily and Monthly Interest) works
Most US cards charge interest with the average daily balance method: the APR is divided by 365 to get the daily periodic rate, which is applied to the average balance for each day of the billing cycle.
If you carry the balance, unpaid interest is added and earns interest too. Paying the full statement balance by the due date usually avoids interest on purchases.
The formula
Worked example
Using the default values shown in the calculator:
| Average daily balance | $3500 |
|---|---|
| Card APR | 24.99 % |
| Days in the billing cycle | 30 |
- 3,500 at 24.99% APR costs $2.40 a day and $71.89 over a 30-day cycle.
- Carried for a year: $982.28.
Result:
| Interest per day | $2.40 |
|---|---|
| Interest this billing cycle | $71.89 |
| Interest over a year if the balance stays (compounding monthly) | $982.28 |
| Daily periodic rate | 0.07% |
Frequently asked questions
How do I avoid credit card interest?
Pay the full statement balance by the due date every month. Cash advances usually start charging interest immediately.
Sources and further reading
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This calculator gives estimates for information only. It is not financial advice, and your lender's or provider's figures will govern. Rates, fees and rules vary. See our disclaimer.