Credit Card Interest Calculator
Credit card interest calculator: interest charged in a billing cycle from the average daily balance, APR and number of days.
I = B · APR365 · d
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
Card issuers divide the APR by 365 to get a daily rate and apply it to your average daily balance. Paying the full statement balance avoids interest.
Formula
I = B · APR365 · d
| Symbol | Quantity | Units |
|---|---|---|
| B | Average daily balance | $, €, £ |
| APR | APR | %, × |
| d | Days in billing cycle | — |
| I | Interest charged | $, €, £ |
Worked example
Given: B = 3,000.00 $ · APR = 24 % · d = 30
I = B · APR · d365
Result: I = 59.18 $
Interest charged for different values of Average daily balance
| B · Average daily balance | I · Interest charged |
|---|---|
| 1,500.00 $ | 29.59 $ |
| 2,250.00 $ | 44.38 $ |
| 2,700.00 $ | 53.26 $ |
| 3,000.00 $ | 59.18 $ |
| 3,300.00 $ | 65.10 $ |
| 3,750.00 $ | 73.97 $ |
| 4,500.00 $ | 88.77 $ |
| 6,000.00 $ | 118.36 $ |
Other values as in the worked example.
Frequently asked questions
$3,000 balance at 24 % APR for 30 days?
About $59.18 of interest.
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