Daily Interest Calculator
Calculate per-diem (daily accrual) interest between two dates or over a day-count, with simple and daily compound interest, and 4 day-count conventions
Enter a principal, an annual interest rate, and either a date range or a plain day count. Day-count conventions affect the result: Actual/365 (Fixed) always divides by 365; Actual/360 divides by 360 (common for many commercial loans, produces slightly higher interest); Actual/Actual divides by 365 or 366 depending on whether the days fall in a leap year (split at Dec 31 if a period crosses a leap-year boundary); 30/360 (Bond Basis) treats every month as having 30 days, a convention common in bond markets. There is no universal standard - the convention used depends on your specific loan/account agreement.
| Type | Interest | Total Amount |
|---|
| Convention | Divisor | Days Used | Interest | Total Amount |
|---|
Educational estimate only, not professional financial advice - actual bank/lender interest calculations may include additional fees, minimum balance rules, or compounding-period nuances not modeled here. Day-count convention significantly affects results, and the convention actually used depends on the specific loan/account agreement - there is no universal standard.
Add any number of scenarios (loans, savings accounts, invoices, etc.) with their own principal, rate, day count, calculation type, and day-count convention, to compare interest accrued side by side.
| Scenario | Principal | Rate | Days | Type | Convention | Interest | Total Amount |
|---|
Educational estimate only, not professional financial advice - actual bank/lender interest calculations may include additional fees, minimum balance rules, or compounding-period nuances not modeled here. Day-count convention significantly affects results, and the convention actually used depends on the specific loan/account agreement - there is no universal standard.