Can 4 people cover a 24/7 roster on 12-hour shifts?

Yes. Splitting 14 twelve-hour shifts among 4 people works out to 42 hours per person per week, which is why the classic 4-team rotations like 2-2-3, Pitman, and 4-on-4-off exist. The 2 hours above a 40-hour week are permanent built-in overtime, and the roster has zero spare capacity, so every absence becomes extra shifts for the remaining 3. It stays under the EU Working Time Directive's cap of an average 48 hours a week.

Is it better to run 4 people at 42 hours or 5 at 33.6 hours?

4 at 42 hours gives you full-time contracts and a clean rotation but bakes 2 hours of weekly overtime into every contract and leaves no absence cover. 5 at 33.6 hours gives you slack for sickness and vacation but puts everyone below full-time hours, which usually means part-time contracts or paying for overlap. If your absence rate is anywhere near the 25% buffer the arithmetic assumes, the fifth person costs less than the overtime and fatigue of running 4.

Can 3 people cover 24/7 with 12-hour shifts?

Not legally in the EU and not sustainably anywhere. Splitting 168 weekly hours among 3 people works out to 56 hours per person per week, which exceeds the EU Working Time Directive's cap of an average 48 hours a week. Treat a 3-person 24/7 roster as a short emergency posture, not a schedule.

Do 12-hour shifts meet the EU 11-hour daily rest requirement?

Yes, by construction. A 24/7 roster on 12-hour shifts has only 2 handover times a day, so the gap between one shift and the next is always at least 12 hours, which clears the EU requirement of 11 hours of daily rest between shifts. The rule to actually monitor is the cap on average weekly hours at 48, especially when a 4-person roster at 42 hours absorbs absences as overtime.

All staffing scenarios

Staffing 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.

The short answer

Covering 24/7 with one person on duty means staffing 168 hours a week: a minimum of 5 employees at 33.6 hours each, and realistically 6 once holidays, sickness, and training are priced in.

Coverage window: 24/7
Hours to staff / week: 168
Shift length: 12h
Shifts to fill / week: 14
Bare minimum: 5 people
With absence buffer: 6 people

Why the math lands there

Staffing one position around the clock means filling every one of the week's 168 hours. Cut it into 12-hour shifts and you get 2 per day, 14 slots a week to fill. Against 40-hour contracts those 168 hours come to 4.2 full-time equivalents. You cannot hire 4.2 people, so the minimum roster is 5 employees at 33.6 hours each, and the realistic number is 6 once you carry a 25% buffer for vacation, sickness, and training.

In practice almost nobody staffs this with 5. The industry default is 4 people at 42 hours each, and the entire canon of 4-team rotations, 2-2-3, Pitman, DuPont, 4-on-4-off, exists to make that exact arithmetic work. The 2 hours above a standard week are accepted as built-in overtime, the price of full-time contracts and a clean repeating rotation. The alternative, 5 at 33.6 hours, means part-time contracts or paying people for hours you do not need, which is why the 4-team model keeps winning.

Twelve-hour shifts also keep the structure minimal. There are only 2 handovers a day, and every off-duty gap is at least 12 hours, so the EU rule requiring 11 hours of daily rest between shifts is met by the shape of the schedule itself. What the shift length costs you is fatigue at the back end of nights, and that is the part the arithmetic does not price in.

124 hours a day times 7 days a week = 168 coverage hours to staff every week.
2168 hours divided into 12-hour shifts = 14 shifts to fill every week.
3168 hours divided by a 40-hour workweek = 4.2 full-time equivalents, so 5 employees minimum.
4Nobody works every scheduled week. With a typical 20 to 25 percent allowance for leave, sickness, and training, plan for 6 people to keep the roster from running on overtime.

Headcount options, side by side

The same 168 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
3	56	4.7	Over legal limits in most countries
4	42	3.5	Built-in overtime
5this page	33.6	2.8	Standard workload
6	28	2.3	Slack for absence
7	24	2	Slack for absence
8	21	1.8	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.

2-2-3 schedule (Panama)

The 2-2-3 is the gentlest way to make 4 people at 42 hours cover 14 twelve-hour slots: nobody works more than 3 shifts in a row, and every other weekend is fully off, across a 28-day cycle.

12h shifts · 4 teams · avg 42h/week

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Pitman schedule

Pitman fills the same 14 slots with 4 teams averaging 42 hours, but compresses the rotation into a 14-day cycle and turns every other weekend into a 3-day weekend.

12h shifts · 4 teams · avg 42h/week

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4-on-4-off schedule

4-on-4-off is the bluntest answer to 14 slots and 4 people: fixed blocks of 4 on and 4 off on a 16-day cycle, averaging 42 hours, easy to memorize and heaviest on the fourth consecutive 12-hour shift.

12h shifts · 4 teams · avg 42h/week

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What the arithmetic does not tell you

4 people at 42 hours is a roster with no slack. Fourteen slots divided by 4 leaves zero uncovered shifts and zero spare capacity, so every sick day is repaid by someone returning on a scheduled day off, at overtime rates on top of the 2 hours of overtime already baked into each week. The 25% absence buffer that turns a 5-person minimum into a realistic 6 does not vanish when you run 4 teams. It moves into your overtime line and your team's rest days.

The arithmetic treats hour 1 and hour 12 of a night shift as identical. They are not. Twelve-hour nights concentrate fatigue exactly where a lone worker has no colleague to catch a mistake, and the 4-team rotations all schedule blocks of consecutive nights to make the pattern come out even. If you are weighing 4 at 42 hours against 5 at 33.6, count the fifth person as fatigue relief on night blocks, not as 33.6 hours of production.

Compliance is the easy part of this configuration, and that can mislead. With 2 fixed handovers, every off-duty gap is 12 hours or more, so the EU requirement of 11 hours of daily rest is satisfied without anyone checking. The constraint that actually binds is the EU cap on average weekly hours at 48: rotations at 42 hours clear it, the 3-person option at 56 hours does not, and a 4-person roster absorbing a long absence can drift toward it faster than the published schedule suggests.

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 24/7 with 12-hour shifts?: 24/7 coverage with one person always on duty is 168 hours a week, or 14 twelve-hour shifts. At a 40-hour target week that is 4.2 full-time equivalents, so the minimum is 5 employees at 33.6 hours each and the realistic number is 6 once you add a 25% absence buffer. Most operations run 4 people at 42 hours each instead, using a 4-team rotation.
Can 4 people cover a 24/7 roster on 12-hour shifts?: Yes. Splitting 14 twelve-hour shifts among 4 people works out to 42 hours per person per week, which is why the classic 4-team rotations like 2-2-3, Pitman, and 4-on-4-off exist. The 2 hours above a 40-hour week are permanent built-in overtime, and the roster has zero spare capacity, so every absence becomes extra shifts for the remaining 3. It stays under the EU Working Time Directive's cap of an average 48 hours a week.
Is it better to run 4 people at 42 hours or 5 at 33.6 hours?: 4 at 42 hours gives you full-time contracts and a clean rotation but bakes 2 hours of weekly overtime into every contract and leaves no absence cover. 5 at 33.6 hours gives you slack for sickness and vacation but puts everyone below full-time hours, which usually means part-time contracts or paying for overlap. If your absence rate is anywhere near the 25% buffer the arithmetic assumes, the fifth person costs less than the overtime and fatigue of running 4.
Can 3 people cover 24/7 with 12-hour shifts?: Not legally in the EU and not sustainably anywhere. Splitting 168 weekly hours among 3 people works out to 56 hours per person per week, which exceeds the EU Working Time Directive's cap of an average 48 hours a week. Treat a 3-person 24/7 roster as a short emergency posture, not a schedule.
Do 12-hour shifts meet the EU 11-hour daily rest requirement?: Yes, by construction. A 24/7 roster on 12-hour shifts has only 2 handover times a day, so the gap between one shift and the next is always at least 12 hours, which clears the EU requirement of 11 hours of daily rest between shifts. The rule to actually monitor is the cap on average weekly hours at 48, especially when a 4-person roster at 42 hours absorbs absences as overtime.

How many employees do you need to cover 24/7 with 8-hour shifts?

168 hours a week divided into 21 eight-hour shifts is 4.2 FTE, and that fraction is the whole problem.

168 hours/week · 8h shifts

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What is the best 24/7 shift pattern for 4 people?

Four people at 42 hours each is the classic small-team 24/7 staffing level, and the pattern choice matters more than the headcount math.

168 hours/week · 12h shifts

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How do you cover 24/7 with 5 people?

On paper it is 33.6 hours each; in practice it is a 4-team rotation plus one person on relief.

168 hours/week · 12h shifts

See the math →