How to Calculate Working Hours and Overtime

Works out time on site and actual working time from clock-in, clock-out and break minutes. Anything beyond the contracted hours counts as overtime, and an earlier clock-out is taken as the next day.

This tool works out how long was actually worked, and how much of it counts as overtime, from the clock-in and clock-out times and the break.

W=(M2M1)BW = (M_2 - M_1) - B

Here M1M_1 is the clock-in time in minutes, M2M_2 the clock-out time in minutes, BB the break in minutes and WW the working time. The span from arrival to departure is the time on site, and taking off the break leaves the time actually worked.

O=max(0,W60C)O = \max(0, W - 60 C)

Here CC is the contracted hours and OO the overtime. A short day gives zero rather than a negative figure.

Worked example

Clocking in at 09:00 and out at 19:30, with a 60 minute break against contracted hours of 8, gives 9 hours 30 minutes worked, 1 hour 30 minutes of overtime and 10 hours 30 minutes on site.

The time on site is 630 minutes, and taking off the break leaves 570 worked. Eight contracted hours are 480 minutes, so 570 − 480 = 90 minutes of overtime.

Breaks

Japanese labour law requires a break of at least 45 minutes once the working time passes six hours, and at least an hour once it passes eight. Breaks do not count as working time. Other countries set their own minima, but the arithmetic is unchanged.

Points to watch

The overtime given here is time beyond the contracted hours. Statutory overtime, which attracts a premium rate, is time beyond eight hours in a day or forty in a week. Where the contract is shorter than eight hours the two figures differ, and only the statutory one carries the premium.

Night and holiday premiums are not part of this calculation.