Two-shift and three-shift systems
In a two-shift system, early and late shifts alternate, usually week by week. A three-shift system adds the night shift, typically three 8-hour shifts such as 6 AM–2 PM, 2 PM–10 PM and 10 PM–6 AM.
If work happens only Monday to Friday, it is called semi-continuous shift work.
Continuous shifts
In fully continuous shift work, operations run around the clock, seven days a week. Several teams take turns in a fixed rhythm so that every shift is covered on weekends and holidays, too. A common pattern is 2-2-2-2: two early, two late, two night shifts, then two days off.
12-hour patterns compared
Many plants, hospitals and emergency services work 12-hour shifts. The three most common patterns:
| Pattern | Rhythm | Cycle | Avg. hours per week |
|---|---|---|---|
| 4 on 4 off | 4 days on, 4 days off | 8 days | 42 |
| 2-2-3 | 2 on, 2 off, 3 on, 2 off, 2 on, 3 off | 14 days | 42 |
| DuPont | 4 nights, 3 off, 3 days, 1 off, 3 nights, 3 off, 4 days, 7 off | 28 days | 42 |
How to check the weekly hours
With 4 on 4 off you work 4 × 12 = 48 hours in 8 days. Per week that is 48 ÷ 8 × 7 = 42 hours. With the 2-2-3 pattern it is 7 shifts of 12 hours in 14 days, so 84 hours in two weeks – also 42 per week.
A note on Germany: whether 12-hour shifts are permitted there depends on the individual case. The Working Hours Act (ArbZG) generally allows 8 hours per working day, up to 10 at most; longer shifts are only possible with exceptions, for example from a collective agreement.