Forty hours a week with rotating days, swings and nights. Model overtime against the FLSA regular rate, with shift differential folded in before the multiplier.
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Standard FLSA: overtime applies after 40h in any Sun–Sat workweek within this period.
Gross Pay — This Period
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A five-day rotating eight-hour schedule is the oldest continuous-operations pattern still in wide use — three shifts a day, crews rotating through days, swings and nights on a weekly or monthly cadence. Forty scheduled hours a week means the roster itself is designed to produce no overtime, which makes it the pattern where almost all overtime comes from holdovers, coverage and the rotation changeover.
It is also the pattern where the most money goes missing, and the reason has nothing to do with how many overtime hours you worked. It is about what rate those hours were multiplied by.
The Fair Labor Standards Act requires overtime at one and a half times the regular rate, and the regular rate is not the same thing as the base wage on your offer letter. It is total straight-time compensation for the workweek divided by total hours worked, and it must include shift differentials, hazard pay, non-discretionary bonuses and most other premiums tied to the work performed.
Work the example. Base wage $32 an hour, a 48-hour week, with 24 of those hours worked on nights carrying a 10% differential of $3.20 an hour. Straight-time compensation is 48 hours at $32, or $1,536, plus $76.80 in differential — $1,612.80. Divide by 48 hours worked and the regular rate is $33.60, not $32. The overtime premium owed on the eight overtime hours is half the regular rate applied to those hours, $134.40, for a total of $1,747.20.
Now do it the way many payroll systems still do it: forty hours at $32, eight hours at $48, plus the differential — $1,740.80. The gap is $6.40 for one week. It looks trivial. Across a year of rotating nights with regular holdovers it runs into several hundred dollars, and because it is a systematic calculation error rather than a missed shift, it applies to every affected employee in the plant simultaneously.
If your employer pays a flat per-shift differential rather than a percentage, the same rule applies — the flat amount is divided across the hours worked and folded into the regular rate before the multiplier. Enter your differential as a percentage here and compare the resulting effective hourly rate against your stub. If your stub's overtime line divides out to exactly 1.5 times base on a week containing differential hours, that is the discrepancy.
The second source of overtime on this pattern is structural. When a crew rotates from one shift to another, the changeover frequently produces a compressed turnaround, and depending on how the rotation is anchored against the workweek, a crew can end up with six shifts inside a single Sunday-to-Saturday period — 48 hours, eight of them at premium, in a roster advertised as forty.
Changeover weeks are easy to miss when you are estimating annual earnings, because they occur only at the rotation interval rather than every week. Step through a full rotation using the period arrows rather than modelling a single representative fortnight.
Rotation direction matters here too. A forward or clockwise rotation moves crews days to swings to nights, giving crews a longer rest at each changeover. A backward rotation moves nights to swings to days and compresses the turnaround to as little as eight hours. Backward rotations therefore produce more double-backs, and double-backs are where holdover overtime concentrates — a crew already short on rest is the crew most likely to be held over when relief calls off.
Some contracts pay a quick-turnaround or short-rest premium on top of the ordinary rate when the gap between shifts falls below a set number of hours. That premium is compensation tied to the work performed, so it belongs in the regular rate alongside the shift differential, and the same calculation trap above applies to it. If your contract has one, fold it into the differential percentage here rather than treating it as a separate flat line.
An employer must establish a fixed, regularly recurring 168-hour workweek, and it may choose any start day and hour it likes. What it may not do is move that boundary in order to reduce overtime liability. On a rotating schedule, where hours land near the threshold every week, a shifting boundary is unusually profitable for an employer and unusually hard for an employee to spot.
The workweek start is printed on most pay stubs. Set the cycle start date in this calculator to match it, and the weekly grouping here will mirror how your employer is actually required to count.
