Shift schedule calendar: 2-2, 4-on-4-off and 24/72 rotations

Between 14 and 16 — it depends on which day of the cycle falls on the 1st. A 31-day month that starts on a workday has 16 shifts, 192 hours on 12-hour shifts; a 28-day February always has exactly 14. Over a full year it averages 42 hours a week.

Only the time inside the night window counts as night work, and the default window is 22:00–06:00 — 8 of the 12 hours. A break is placed in the middle of the shift, so with a one-hour break 7 night hours remain. If your law or contract defines night differently, change the window under "Working time accounting".

By calendar date, the way a timesheet does it: a shift that starts on the 31st at 20:00 gives 4 hours to the last day of the month and 8 hours to the 1st of the next. 24-hour shifts are split the same way.

Each of them works half or a quarter of the days with shifts long enough to land on the same average: 12 hours every other day, or 24 hours every fourth day, is 84 hours per two weeks. The tool shows the average for the month or year you are looking at, so short and long months are visible.

Choose the number of crews and the tool offsets each one evenly through the cycle. Day-night-sleep-off with 4 crews puts one crew on days and one on nights every single day; the "working" row in the table shows any day nobody covers, and the + and − buttons move a crew by one day.

Tap "To phone calendar (.ics)" for the month or the year and open the file: Google Calendar, iPhone Calendar and Outlook add each shift as an event with its start and end. The times carry no time zone, so an 08:00 shift stays at 08:00 wherever your phone is.