Method and sources
How we calculate
- Every rule comes from the source listed below and is explained on the calculator's page.
- The calculation runs in your browser; the page shows the working with your numbers.
- Results are rounded only when they are displayed.
How we check
- Every rule has test cases with values taken from its source.
- All tests run automatically before each release; if one fails, nothing is published.
- Every number in tables and examples comes from the same code as the calculator.
Sources
| Rule | Source | Verified on |
|---|---|---|
| Hours between two times, clock-out time and decimal hours (R1, R2) | BIPM, The International System of Units (SI), 9th edition, Table 8 | |
| Paid rest breaks and unpaid meal periods (R10) | 29 CFR 785.18 Rest and 785.19 Meal (FLSA hours worked) | |
| Days until a date, leap years (R4) | ECMAScript 2025 Language Specification, ยง21.4.1.5 DaysInYear (Gregorian calendar) | |
| Christmas Day as a federal holiday and its observed day (R5) | 5 U.S.C. 6103, Holidays | |
| Hours from now across daylight saving changes (R3) | 15 U.S.C. 260a, Advancement of time or changeover dates |
Found a mistake?
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