Plan 12-hour rotations: hours per week, hours over a full cycle and how many people you need for round-the-clock coverage.
Paid hours per shift = shift length − unpaid break.
Average weekly hours = shifts per cycle × paid hours ÷ cycle days × 7.
People needed = (positions × hours per day × 7) ÷ shift length ÷ average shifts per person per week, rounded up. Add a buffer for vacation, sickness and training.
A security company covers two posts 24 hours a day with a 2-2-3 rotation, 12-hour shifts and a 30-minute unpaid break. Each person works 7 shifts in 14 days, 80.5 paid hours per cycle or about 40.25 a week. The posts need 336 shift-hours a week, which is 28 shifts. Each person averages 3.5 shifts a week, so the minimum is 8 people, before allowing for leave.
Use it when you consider moving a team from 8-hour to 12-hour shifts, when you set up a 24/7 post, or when you check how many hours a rotation gives each person over the cycle.
Long shifts can mean overtime in some weeks of a rotation, and daily overtime rules apply in some states. Check the rules for your location and your workforce.
A 911 dispatch center needs one console staffed 24 hours a day on a 4 on, 4 off rotation with 12-hour shifts and a 45-minute unpaid meal break. Paid time is 11.25 hours a shift, 45.00 hours per 8-day cycle, or an average of 39.38 hours a week. One post needs 168 shift-hours a week, which is 14 shifts. Each dispatcher averages 3.5 shifts a week, so the minimum is 4 people, with nobody left over to cover vacation.
People needed is a floor that assumes everyone works every scheduled shift, so add relief staff for vacation, sickness and training before you hire. Average weekly hours hide the uneven weeks: rotation shifts are not spread evenly across the cycle, so one workweek can pass 40 hours even when the average does not. The headcount divides by the full shift length, so if shifts overlap for handover, count the overlap as extra coverage hours.
Under federal rules, overtime is generally based on hours over 40 in a workweek, so some weeks of a rotation may include overtime. Some states, such as California, also have daily overtime rules.
It depends on coverage needs and what employees prefer. 2-2-3 gives every other weekend off; 4-on-4-off has longer stretches.
Vacation, sick days and training mean you need more people than the bare minimum.
Short rest breaks are often paid and meal periods often unpaid. Rules vary by state.
Seven shifts every 14 days works out to 182.5 shifts a year. At 12 paid hours that is 2,190 hours, and with a 30-minute unpaid break it is 2,098.75 hours, both above the 2,080 hours of a standard 40-hour week.
If balances are kept in hours, one shift off uses 12 hours of leave, or 11.5 if your policy charges only paid hours. Employees moving from 8-hour shifts will see the same balance cover fewer days off, so explain the conversion before the switch.
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