| What you are comparing | In this illustration |
|---|---|
| Assumed balance and yearly rate | $10,000 at 12% |
| 30 days using a 365-day year | $98.63 interest |
| 30 days using a 360-day year | $100.00 interest |
$10,000 × 12% × 30 days ÷ 365 = $98.63
Follow the denominator
The first method is $10,000 × 12% × 30 ÷ 365. The second uses the same balance, annual rate and days, but divides by 360. That difference alone produces $98.63 versus $100.00, with the stated rounding.
To check an actual statement, find the contract’s day-count method, posting dates, relevant balance and rounding rules. These calculations explain a difference; they do not establish which convention your lender may lawfully use.
This is a saved illustration with stated assumptions, not an offer or prediction for your circumstances. The full calculation and original limitations are in the optional archive.
Explore the complete interest fees and debt mathematics guide →