Methodology

How clock times are parsed

A clock time is converted to a single integer: seconds since midnight. 08:30 becomes 30,600; 17:15 becomes 62,100. Both 24-hour (17:15) and 12-hour (5:15 PM) formats are accepted, with seconds optional. Hours are validated as 0–23 (or 1–12 with AM/PM) and minutes and seconds as 0–59.

How overnight durations work

If the end time is earlier than the start time, the end is treated as the next day and 86,400 seconds (24 hours) are added. 22:00 → 06:00 is therefore 8 hours, and 23:30 → 00:30 is 1 hour. Calculators that expose advanced options let you force “same day” handling, which returns a clear validation message instead. No timezone conversion is involved — clock times are compared in the same local context.

How breaks are deducted

A break is entered either as minutes or as a break start/end range — never both, so a break is never deducted twice. Break seconds are subtracted from the gross duration. If the break is longer than the shift, the calculator reports a validation message rather than producing a negative day.

How decimal hours are calculated

Decimal hours = hours + minutes ÷ 60 (+ seconds ÷ 3600). 7 hours 30 minutes is 7 + 30 ÷ 60 = 7.5 decimal hours. Decimal conversion happens only at the display step, so intermediate arithmetic never accumulates floating point error. Note that 7:30 is not 7.30.

How rounding works

Rounding is opt-in and off by default. When enabled (1, 5, 6, 10 or 15 minutes), a duration is rounded half-up to the nearest step, deterministically: 8h 02m rounds to 8h 00m at 5 minutes; 8h 03m rounds to 8h 05m; 8h 07m rounds to 8h 00m at 15 minutes; 8h 08m rounds to 8h 15m. Rounding rules can vary by employer and jurisdiction — the choice is yours.

How the overtime split works

Total time up to the weekly threshold is regular; everything above it is overtime. With a 40-hour threshold: 38 hours → 38/0, 40 hours → 40/0, 43.5 hours → 40 regular + 3.5 overtime. The optional pay estimate multiplies your hourly rate and overtime multiplier using integer-cent arithmetic. Overtime rules vary by country, state, employer and employment type; this calculator is arithmetic only, not legal, payroll or tax advice.

Privacy

All calculations and exports happen in your browser. The times you enter are never uploaded and are never attached to analytics events.

Limitations

• No timezone conversion — clock times are compared in one local context
• No tax withholding, net pay, or labour-law compliance decisions
• No daily overtime rules; the split is weekly arithmetic on the total you enter
• Durations from a single clock-time range are limited to 24 hours; add multiple durations for more