Comment ça marche
Time arithmetic is not decimal arithmetic, and mixing them is the source of most timesheet errors. An hour has sixty minutes, so 1 hour 45 minutes is 1.75 hours in decimal, not 1.45. Payroll systems vary in which they want: hourly rates multiply against decimal hours, while scheduling and compliance rules are usually expressed in hours and minutes. The calculator reports both, along with the raw minute total, so a figure can be entered into any downstream system without converting it by hand — a conversion that goes wrong often enough to be worth eliminating.
An overnight shift is the classic edge case. A shift starting at 22:00 and ending at 06:00 gives a negative difference under naive subtraction. The fix is to detect that the end time is earlier than the start time and add twenty-four hours, which yields the correct eight-hour duration. The subtlety is that this is a heuristic: it assumes no single shift exceeds twenty-four hours, which is true for every real employment context and false for a mis-keyed entry, so the calculator flags the situation rather than silently adjusting it.
Rounding is where policy meets arithmetic and where the two most common methods differ. Rounding each punch to the nearest increment and then subtracting — the method most time clocks use — can produce a total that differs from rounding the total duration. Rounding a 7-minute-late arrival down to the quarter hour is generous to the employer, and the practice is regulated in some jurisdictions: the United States Fair Labor Standards Act, for instance, permits rounding to the nearest five minutes or a quarter hour provided it does not systematically favour the employer over time. The calculator applies the rounding per row and states which method it used.
Overtime is a threshold applied to the total rather than to each row, because the qualifying period is normally a day or a week and the rows are just its parts. The calculator applies a configurable threshold, splits the total into regular and overtime hours, and prices each at its own rate, with overtime defaulting to 1.5 times the base as the common convention. Whether a particular threshold and multiplier is lawful depends on the jurisdiction and on the employment contract, which is why both are inputs rather than fixed assumptions.
Cas d'usage courants
- Total a week of timesheet rows and export them as CSV for payroll.
- Work out the hours between two clock times for a shift, excluding an unpaid lunch break.
- Calculate an overnight shift that crosses midnight without a negative result.
- Convert a timesheet into decimal hours for an invoice or a billing system.
- Split a week into regular and overtime hours at a forty-hour threshold.
- Check that a set of logged hours matches the total on a payslip.
Dernière mise à jour: 2026-10-14 — le corps de l'article est affiché en anglais ; l'interface est traduite.