How it works
Use the average daily balance for each interest-bearing category, not necessarily the ending statement balance. The purchase and cash-advance categories can have different APRs. This model applies their daily periodic rates over the selected cycle and then adds separately entered fees.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Purchase average daily balance | $1,000.00 | Required unit: $. Use a non-negative value. |
| Purchase APR | 24 % | Enter the percentage as a number: for 15%, enter 15. Use a non-negative value. Allowed range: 0–100. |
| Cash-advance average daily balance | $200.00 | Required unit: $. Use a non-negative value. |
| Cash-advance APR | 30 % | Enter the percentage as a number: for 15%, enter 15. Use a non-negative value. Allowed range: 0–100. |
| Days in the billing cycle | 30 days | Required unit: days. Use a whole number. Must be greater than zero. Allowed range: 1–365. |
| Contract daily-rate denominator | 365 days | Check the selected option before calculating. |
| Separate fees in this cycle | $0.00 | Required unit: $. Use a non-negative value. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Purchase average daily balance
- $1,000.00
- Purchase APR
- 24 %
- Cash-advance average daily balance
- $200.00
- Cash-advance APR
- 30 %
- Days in the billing cycle
- 30 days
- Contract daily-rate denominator
- 365 days
- Separate fees in this cycle
- $0.00
Complete example results
- Estimated cycle interest plus entered fees
- $24.66
- Purchase interest
- $19.73
- Cash-advance interest
- $4.93
- Entered fees
- $0.00
Reading the result
Match the rate period to the payment period. Fees and taxes absent from the inputs are not added automatically; compare totals with the same cost coverage.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
Will paying the closing balance produce this exact interest charge?
Not necessarily. Grace periods, actual transaction dates, payment allocation and the issuer’s balance method matter. Enter only balances that are subject to interest, and use the denominator in the contract. The calculator does not rebuild a transaction-by-transaction ledger.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method sources: consumerfinance.gov · consumerfinance.gov