Credit Card Interest Calculator
Calculate the daily and monthly interest charged on a card balance.
Please note: An estimate. Interest is usually charged daily on the balance after any grace period, and cash advances and balance transfers often carry different rates.
What the Credit Card Interest Calculator does
Card issuers convert the APR into a daily periodic rate, apply it to your average daily balance, and multiply by the days in the cycle. Carrying any balance forward usually forfeits the interest-free grace period on new purchases too.
Formula
Daily periodic rate = APR ÷ 365Interest = Average daily balance × DPR × Days in cycle
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Average daily balance | selected currency | Yes | Accepts more than 0. |
| APR | % | Yes | — |
| Days in the billing cycle | number | Yes | Accepts 1 or more, up to 62. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Currency.
- Enter Average daily balance, APR and Days in the billing cycle.
- Select Calculate.
Worked example
A $3,000 average balance at 22.9% APR over a 30-day cycle.
- Balance
- 3000
- APR
- 22.9
- Days
- 30
DPR 0.06274%, interest = 3,000 × 0.0006274 × 30 = $56.47.
Frequently asked questions
How do I avoid card interest entirely?
Pay the full statement balance by the due date every month. The grace period then keeps purchases interest-free.
What is the average daily balance?
The sum of each day's balance divided by the days in the cycle. Paying earlier in the cycle lowers it and cuts the charge.