Compute credit card interest for a month and over a payoff period.
Please do not make financial decisions based on these results.
What is the Credit Card Interest Calculator?
Compute credit card interest for a month and over a payoff period. To use the Credit Card Interest Calculator, enter balance, apr, days in cycle; it returns interest this cycle, interest per year at this balance, daily interest, and shows them instantly as you type.
Paying debt down
Extra payments shorten a loan and cut interest. Use the repayment calculator for one loan and the debt payoff calculator when you owe several. Credit cards are a special case; see the credit card payoff calculator.
How to use the Credit Card Interest Calculator
- Fill in the fields. You will need Balance ($), APR (%), Days in cycle. Take the rate and term from your loan offer. Fees and the rate type change the result. Fields marked optional can stay at zero.
- Read the result. The highlighted box gives the Interest this cycle, and the cards below show Interest per year at this balance, Daily interest. Tables and charts break it down further.
- Test other scenarios. Results update as you type. Change one value at a time to see what drives the answer, and press Reset to go back to the defaults.
Formula and how it works
Example with real numbers
Here is the Credit Card Interest Calculator using the default values shown in the calculator above:
Inputs
| Balance ($) | 4,500 |
|---|---|
| APR (%) | 23.9 |
| Days in cycle | 30 |
Results
| Interest this cycle | $88.40 |
|---|---|
| Interest per year at this balance | $1,075.50 |
| Daily interest | $2.95 |
With these inputs the calculator returns Interest this cycle: $88.40. Change any value in the calculator to see how the result moves.
What if you change one input?
Sensitivity check: raising Balance ($) from 4,500 to 5,400 (about 20% higher) and leaving everything else as in the example above changes the results like this:
| Result | Example | After the change | Change |
|---|---|---|---|
| Interest this cycle | $88.40 | $106.08 | +20% |
| Interest per year at this balance | $1,075.50 | $1,290.60 | +20% |
| Daily interest | $2.95 | $3.54 | +20% |
The input that moves the result most is the one to check twice. Change it in the calculator above to test your own case.
What the results tell you
The results panel of the Credit Card Interest Calculator reports Interest this cycle, interest per year at this balance and daily interest. Compare these figures while changing one input at a time, and use the related calculators below to look at the same situation from another angle.
Method and limits. This calculator applies the formula in the section above to your inputs, in your browser; nothing you enter is stored on our servers. Your lender’s offer is the final word: fees, rate type and rounding differ between lenders. It is for information, not financial, tax or legal advice.
Frequently asked questions
How is card interest calculated?
Usually daily on your average balance at APR ÷ 365.
How can I pay off a loan faster?
Pay more than the required amount, add extra yearly or one-time payments, or switch to biweekly payments. Make sure extra payments go to principal.
What is APR and why does it matter?
APR is the yearly cost of a loan including fees. Use it, rather than the interest rate alone, to compare offers.
Are the results guaranteed?
No. Results depend entirely on the numbers you enter and the formulas shown on this page. Please do not make financial decisions based on them alone; confirm important figures with a licensed professional.
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