4 on, 4 off schedule

How the 4 on, 4 off rotation works

The cycle is eight days: four consecutive 12-hour shifts, then four consecutive days off. Two crews are enough to cover a 12-hour operation, because when crew A is working its four days crew B is on its four off. A 24-hour operation adds a second pair on nights, or rotates each crew through days and nights on alternate blocks.

The distinctive feature is that the cycle is not a multiple of seven. Eight days means your four working days slide through the week: if this block runs Monday to Thursday, the next starts Tuesday, the one after Wednesday, and so on. Every eight weeks you have worked and had off every day of the week the same number of times, which is what makes the pattern fair, and also why it is hard to hold a standing weekday commitment.

Many employers run the four days as two days and two nights instead of four of one kind, which keeps the four-day break but adds a mid-block flip. The calendar here shows four of the same kind; the hours and overtime are identical either way.

Hours, overtime, and what it pays

Four shifts of 12 hours is 48 hours per 8-day cycle, an average of 42 a week. Because eight days is not a whole week, the calendar weeks come in runs: four weeks in a row that each contain four shifts (48 hours), then four weeks that each contain three (36 hours). Where those runs fall depends on which day your employer's workweek starts, and the table above shows the resulting range in weeks over 40 and overtime hours.

A 48-hour week carries 8 overtime hours at a 40-hour threshold, paid at time and a half on your regular rate, differentials included. Some employers with 12-hour crews adopt an 80-hour, two-week reference under a collective agreement, and some annualise hours; neither removes the FLSA obligation for hourly non-exempt staff in the United States, though annualised hours are common practice in the United Kingdom, where this pattern is most widespread.

If your employer pays a night differential and you rotate two days then two nights, half your hours attract it. If you are on fixed nights, all of them do, and your overtime rate must include it.

Who uses it and why

Four on, four off is the default 12-hour pattern for police and fire services in the United Kingdom, and it has spread through ambulance trusts, airports, security contractors, distribution centres and manufacturing plants there and in Canada and Australia. In the United States it shows up in EMS agencies that run 12-hour units, in factories that want two crews on days, and in security and facilities work.

People choose it for the break: four days off every eight is long enough to travel or work a second job, and the working blocks are short enough that fatigue does not build the way it does on longer stretches. Employers choose it because it is trivially simple to roster and every crew gets an identical deal.

Pros and cons

Why it is loved, and why some people leave it.

• —Pro: a four-day break every eight days, all year.
• —Pro: the simplest 12-hour pattern to schedule and to remember.
• —Pro: perfectly fair across crews; weekends and weekdays even out over eight weeks.
• —Con: your working days slide through the week, so no regular weekly commitments.
• —Con: four twelves in a row is a long block, especially on nights.
• —Con: 42 hours a week on average, with runs of 48-hour weeks that each carry 8 overtime hours.

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