How four crews on 12-hour shifts cover every hour of the week, how the common patterns differ, and what changes when you make the switch.
Schedule GuideA 12-hour 24/7 schedule uses four crews: two are working at any moment, one on days and one on nights, while the other two are off. Every crew averages 42 hours a week and works about 182 shifts a year. The common patterns — the DuPont, the 2-2-3 and the 4-on/4-off — differ mainly in how the days off are grouped. About three in four shift workers in our surveys prefer longer shifts with more days off.
A 12-hour 7-day schedule splits each day into two shifts — typically a day shift and a night shift — and covers all seven days of the week. Because a week has 168 hours and each position needs someone in it the whole time, the work is spread across four crews. Each crew averages 168 ÷ 4 = 42 hours a week.
Every crew works 14 shifts in each 28 days, which is about 182 shifts a year. On a traditional five-day, 8-hour schedule, the same person works about 260 shifts a year. That difference in days at work is the main reason 12-hour schedules have become the norm in so many continuous operations.
All three of the best-known 12-hour patterns use four crews and average 42 hours a week. What separates them is how the days off are grouped — and that is what employees feel most.
| DuPont | 2-2-3 | 4-on/4-off | |
|---|---|---|---|
| Crews | 4 | 4 | 4 |
| Full cycle | 28 days | 14 days (longer in some setups) | 8 weeks |
| Average hours per week | 42 | 42 | 42 |
| Weekends off | 2 of every 4 (two off, then two on) | 2 of every 4 (every other weekend) | 3 full weekends of every 8, plus 2 half weekends |
| Most shifts in a row | 4 | 3 | 4 |
| Longest break | 7 days | 3 days | 4 days |
| Days and nights | Rotating | Fixed or rotating | Fixed or rotating |
Each pattern has its own page with the full rotation: the DuPont schedule, the 2-2-3 schedule and the 4-on/4-off schedule.
The 2-2-3 and the 4-on/4-off can run with fixed crews — a day crew pair and a night crew pair — or with crews that rotate between days and nights. The DuPont rotates by design. In our surveys, about 85% of shift workers prefer fixed shifts to rotating ones, and more than 60% would accept a fixed shift that isn’t their first choice rather than rotate. Rotation still has a place, especially where no one wants permanent nights. See fixed vs. rotating shifts for the trade-offs.
Workers on 12-hour shifts do sleep less on the days they work. But because they have far more days off, our survey data shows they average more total sleep across a four-week period than workers on 8-hour schedules. Where 12-hour schedules cause sleep trouble, the cause is usually the pattern rather than the shift length — for example, night crews on an every-other-weekend-off pattern who flip their sleep every few days. More on this in sleep, alertness and safety in shift work.
Twelve-hour schedules tend to fit continuous operations where the work can be done safely over a long shift, where the workforce values days off, and where management is ready to rework the policies that go with the change. They are a weaker fit where the work is physically punishing, where absences are already hard to cover, or where a large part of the workforce depends on second jobs or fixed family routines that a 12-hour day would break.
A pattern or a rule of thumb is only the starting point. The right answer depends on your coverage needs, your workforce’s preferences, your overtime and absence rates, and the policies that go with the schedule — and most sites end up with a design tailored to them. That analysis is what a Shiftwork Solutions engagement does. Talk with us about your operation, or start with the free Shiftwork Assessment.
