How many people do you need to cover 12 hours a day, 7 days a week with 12-hour shifts?
One 12-hour shift per day, seven days a week: 84 coverage hours, 2.1 FTE, and a straight choice between 2 people at 42 hours or 3 at 28.
The short answer
Covering 12 hours a day, 7 days a week with one person on duty means staffing 84 hours a week: 3 employees at 28 hours each, with enough slack at that headcount to absorb normal holidays and sickness.
- Coverage window
- 12 hours a day, 7 days a week
- Hours to staff / week
- 84
- Shift length
- 12h
- Shifts to fill / week
- 7
- Bare minimum
- 3 people
- With absence buffer
- 3 people
Why the math lands there
Twelve hours of coverage a day for 7 days is 84 coverage hours a week. With 12-hour shifts, that is exactly one shift per day, 7 shifts a week, and zero handovers inside the coverage window. At 40 hours per full-timer, 84 coverage hours works out to 2.1 FTE. Since you cannot roster a tenth of a person, the practical minimum is 3 people at 28 hours each, and the absence buffer calculation also lands on 3.
The real decision sits between two rosters. Two people at 42 hours each means each works 3.5 days a week, alternating weeks of 3 and 4 shifts. That puts both of them over the 40-hour target permanently, with nobody in reserve. Three people at 28 hours each is roomy: everyone stays well under 40, weekend duty rotates three ways, and one person can pick up a colleague's shifts without blowing past any limit. Four at 21 hours is roomier still, but that is a part-time bench, not a core team.
Compared with every other coverage shape, this one is clean. There is no night differential to pay, no handovers to script, and the shift itself can mirror opening hours, 07:00 to 19:00. What the shape does demand is weekends: all 7 days carry a shift, so whoever you hire signs up for regular Saturday and Sunday duty. That makes the 2-versus-3 question as much about who will accept the weekend load as about hours.
- 112 hours a day times 7 days a week = 84 coverage hours to staff every week.
- 284 hours divided into 12-hour shifts = 7 shifts to fill every week.
- 384 hours divided by a 40-hour workweek = 2.1 full-time equivalents, so 3 employees minimum.
- 4Nobody works every scheduled week. With a typical 20 to 25 percent allowance for leave, sickness, and training, plan for 3 people to keep the roster from running on overtime.
Headcount options, side by side
The same 84 weekly coverage hours spread over different team sizes. Average weekly hours per person is the number that decides whether a roster is sustainable, legal, and affordable.
| People | Hours / person / week | Shifts / person / week | Verdict |
|---|---|---|---|
| 1 | 84 | 7 | Not viable |
| 2 | 42 | 3.5 | Built-in overtime |
| 3this page | 28 | 2.3 | Slack for absence |
| 4 | 21 | 1.8 | Slack for absence |
| 5 | 16.8 | 1.4 | Slack for absence |
| 6 | 14 | 1.2 | Slack for absence |
The absence buffer above assumes 20 to 25 percent of paid time goes to leave, sickness, and training. Your own rate decides the real number, which you can work out with our shrinkage calculator.
Rotations that make this work
These are proven patterns for this configuration, each with a full interactive calendar and staffing breakdown.
What the arithmetic does not tell you
The 2-person roster has no slack anywhere. Every shift has exactly one person on it, and the only cover for a sick day is the other person, who by definition is on a day off. A week of vacation leaves the remaining person facing all 7 shifts, 84 hours. The EU Working Time Directive caps average weekly hours at 48, so weeks like that cannot become a routine absence plan. If you run 2, arrange an external relief option before you need it, not after.
The arithmetic also assumes one person can hold the post alone for a full 12 hours. There is no overlapping colleague, so lunch and every other break happen with nobody else on duty unless you schedule cover, and any paid break cover is headcount the 2.1 FTE figure does not include. Back-to-back days are legal in the EU: off at 19:00 and back at 07:00 is 12 hours of rest against the required 11, but that margin is a single hour and commuting lives inside it.
Recruiting for the 3-person version means selling 28-hour contracts that always include weekend work, since 7 daily shifts split across 3 people puts Saturdays and Sundays into everyone's rotation. Some candidates want exactly that. But the day one of them resigns, the two who remain are running the 42-hour roster by default, without having signed up for it. Decide in advance which failure mode you prefer: permanent built-in overtime for 2 people, or a part-time roster you must keep filled at 3.
Once the headcount is settled, the daily work is keeping the roster fair and covered as people swap, call in sick, and take leave. That is the part Soon automates, from constraint-aware auto-scheduling to leave management.
Frequently asked questions
- How many employees do you need to cover 12 hours a day, 7 days a week with 12-hour shifts?
- 12 hours a day across 7 days is 84 coverage hours per week, which means 7 twelve-hour shifts, one per day. Against a 40-hour full-time target that is 2.1 FTE. The practical minimum is 3 people at 28 hours each, which also covers the absence buffer, and the lean alternative is 2 people at 42 hours each with built-in overtime.
- Can 2 people cover a 12-hour shift every day of the week?
- Yes. Two people at 42 hours each cover all 7 shifts, with each person working 3.5 days a week by alternating weeks of 3 and 4 shifts. The tradeoff is that there is no third person to absorb sickness or vacation, so every absence lands on the only other employee.
- Is a 42-hour week legal for this schedule in the EU?
- Yes. The EU Working Time Directive caps average weekly hours at 48, so a 42-hour average sits inside the limit. Daily rest also works out: a shift ending at 19:00 and starting again at 07:00 gives 12 hours off, one hour more than the 11 hours of daily rest the EU requires between shifts.
- Should I hire 2 people at 42 hours or 3 people at 28 hours?
- Hire 2 at 42 hours if budget is tight and you have a reliable external relief option for vacations, because the pair has no internal cover. Hire 3 at 28 hours if you can recruit for part-time contracts that include weekends; everyone stays under 40 hours and the roster absorbs an absence without overtime. A 4-person version at 21 hours each also works, but that is a part-time pool rather than a core team.
- How does the 7-on-7-off pattern work for daytime-only coverage?
- 7-on-7-off is normally a 4-team, 24/7 pattern on a 14-day cycle, but its day side is exactly this roster: 2 people on 12-hour shifts, each working a full week on and then a full week off. Both average 42 hours per week, the same total as alternating 3 and 4 shifts, concentrated into 7 consecutive working days in exchange for 7 consecutive days off.
Adjacent staffing questions
How many employees do you need to cover 16 hours a day, 7 days a week with 8-hour shifts?
Two shifts a day, seven days a week comes to 112 coverage hours, which works out to 2.8 FTE, a minimum of 3 people, and a realistic roster of 4.
112 hours/week · 8h shifts
See the math →How many employees do you need to cover 24/7 with 12-hour shifts?
The math says 4.2 FTE and a minimum of 5 people, but the whole industry runs this on 4 people at 42 hours.
168 hours/week · 12h shifts
See the math →How many employees do you need to cover 24/5 with 12-hour shifts?
120 coverage hours, 10 twelve-hour shifts, exactly 3.0 FTE, and a week that refuses to split evenly.
120 hours/week · 12h shifts
See the math →Your next schedule could take 2 minutes.
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