Overtime Hours Per Year on a 12-Hour Rotation: How to Calculate It (2-2-3 and 4-on-4-Off)

A 12-hour rotation averages 42 hours a week. So the usual back-of-the-envelope answer is "two overtime hours a week, about 104 a year." It is the number that shows up in a lot of schedule calculators, and it is wrong in both directions: for most 12-hour rotations the real figure is at least 208 hours a year, and on the same schedule it can be 520 hours depending on one setting in the payroll system.

The reason is a single rule: federal overtime is counted one workweek at a time, and short weeks do not cancel long ones.

The rule that breaks the average

The federal baseline is time-and-a-half the regular rate for hours worked over 40 in a workweek (DOL Fact Sheet #23). The regulations are explicit that weeks stand alone. 29 CFR § 778.104 says the Act "takes a single workweek as its standard and does not permit averaging of hours over 2 or more weeks." Its own example: 30 hours one week and 50 the next averages 40, and the 10 extra hours in the second week are still overtime.

A 36-hour week and a 48-hour week average 42. The 36-hour week earns no overtime and does not offset the 48-hour week, which owes 8 hours of it.

The other half of the puzzle is what a "workweek" is. 29 CFR § 778.105 defines it as "a fixed and regularly recurring period of 168 hours—seven consecutive 24-hour periods," and says it need not match the calendar week. The employer picks the start day and hour. That choice decides where a 14-day cycle gets cut into two weeks, and with 12-hour shifts that cut matters a lot.

Count the weeks, not the average

With 12-hour shifts, a week's hours can only be a multiple of 12, so the overtime per week is easy to look up:

To find your yearly overtime, work out how many shifts land in each workweek of your cycle, read the overtime off the table, add up the cycle, and multiply by the number of cycles in a year. This is the whole method.

The 2-2-3 (Pitman): the start day changes the answer

The 2-2-3 repeats every 14 days: on 2, off 2, on 3, off 2, on 2, off 3. That is 7 shifts, or 84 hours, per cycle. (The pattern itself is explained in the Pitman schedule.)

Put one crew on a calendar: Monday and Tuesday on, Wednesday and Thursday off, Friday through Sunday on, then Monday and Tuesday off, Wednesday and Thursday on, Friday through Sunday off.

• Workweek starts Monday: week 1 holds Mon, Tue, Fri, Sat, Sun = 5 shifts = 60 hours. Week 2 holds Wed and Thu = 2 shifts = 24 hours. Overtime per cycle: 20 + 0 = 20 hours.
• Workweek starts Wednesday: week 1 holds Fri, Sat, Sun = 3 shifts = 36 hours. Week 2 holds Mon, Tue, Wed, Thu = 4 shifts = 48 hours. Overtime per cycle: 0 + 8 = 8 hours.

Both add up to the same 84 hours. For this crew a Monday or Friday start gives the 60/24 split, and the other five start days give 36/48.

Over a 52-week year there are 26 cycles:

• 60/24 split: 26 x 20 = 520 overtime hours
• 36/48 split: 26 x 8 = 208 overtime hours

That is a 312-hour difference on the same people working the same shifts. Which split your crew gets depends on where your employer's workweek starts and how your crew's pattern lines up with it, so two crews at one site can land differently.

The 4-on-4-off: the start day does not matter

The 4-on-4-off repeats every 8 days: four 12-hour shifts (48 hours) then four days off. Because 8 is not a multiple of 7, the cycle drifts across the calendar week. Over 56 days (7 cycles, exactly 8 workweeks) every workweek start gives the same total: four weeks with 4 shifts (48 hours) and four weeks with 3 shifts (36 hours).

• Overtime per 8 weeks: 4 x 8 = 32 hours
• Per 52-week year: 32 / 8 x 52 = 208 overtime hours

So on a 4-on-4-off, 208 is the floor for a standard 40-hour week, and no choice of start day improves it for the worker or for the employer. The paid hours are about 2,190 a year (365 / 8 x 48), but overtime does not follow 2,190 - 2,080. Only the 48-hour weeks produce it, and the 36-hour weeks do not give anything back. (More on the pattern: 4-on-4-off explained.)

Worked example: the dollars

A control-room operator at a private plant (fictional) earns $32.00 an hour, a single flat rate with no differential or bonus. The overtime rate is 1.5 x $32.00 = $48.00. She works the 2-2-3.

Straight-time pay for the cycle: 84 hours x $32.00 = $2,688.00. The overtime premium is the extra half-rate on each overtime hour: $32.00 x 0.5 = $16.00.

The difference is $3,008 - $2,816 = $192 per cycle, or 26 x $192 = $4,992 a year, and it comes from 12 more overtime hours per cycle at a $16 premium. Straight-time pay alone is 26 x $2,688 = $69,888 a year for 2,184 hours.

What the shortcut would say: 2 hours x 52 weeks = 104 overtime hours, a premium of 104 x $16 = $1,664. The lowest real figure here is 208 hours and $3,328 of premium, double the shortcut.

Can the employer change the start day?

An employer can set one workweek for the whole establishment or different ones for different groups. Once set, the start "remains fixed." It can be changed, but only if the change is meant to be permanent and "is not designed to evade the overtime requirements of the Act" (§ 778.105). The worker-side takeaway is simple: the start day is a fact on file, and you can ask for it. The pay-period dates on your stub are a separate thing; the pay period can be two weeks or a month and the overtime is still counted by workweek.

When this math does not apply

• Hospitals and residential care. The 8/80 system counts overtime over 14 days and after 8 hours a day instead, which gives a different answer. See the 8/80 rule.
• Fire and law enforcement on a 7(k) work period. The overtime threshold is higher and measured over a longer period. See 7(k) overtime.
• Daily overtime states. Some states add overtime after a set number of hours in a day, which can raise a 12-hour shift's pay beyond the weekly count. See 12-hour shifts and daily overtime.
• Differentials and bonuses. Any shift differential or non-discretionary bonus changes the regular rate, so the $16 premium above would be higher. See shift differential vs. overtime and non-discretionary bonuses.
• Contracts. A union agreement or company policy may pay overtime daily, after 8 hours, or on a different schedule. The contract controls where it pays more than the federal minimum.
• Salaried non-exempt roles. Salaried non-exempt pay has its own method; see the salaried non-exempt calculation.

Check your own number in five steps

1. Ask for the workweek start day and hour. It is a specific time on a specific day.
2. List one full cycle on a calendar (14 days for 2-2-3, 8 days repeated to fill 56 for 4-on-4-off) and mark your shifts.
3. Cut it into workweeks from that start time and count the shifts in each.
4. Read overtime off the table (4 shifts = 8 hours, 5 = 20) and add up the cycle.
5. Multiply by the cycles in a year and by your premium (half the regular rate) to get the yearly figure, then compare it to the pay stubs for a cycle you have already worked.

This is general information on federal rules with a fictional example, not legal advice; your agreement and your state's law decide your actual pay.

Laying a rotation against real calendar dates is the quickest way to see which shifts fall in which workweek. Duty Pals, a shift calendar for Android, is now on Google Play, and the free shift pattern calculator on this site shows a 2-2-3 or 4-on-4-off against the calendar so you can count the shifts per week yourself.