Under the Fair Labor Standards Act, a "workweek" is any fixed, regularly recurring period of 168 consecutive hours — seven 24-hour days. It can start any day of the week and any hour of the day. Once set, it has to stay consistent. Here's why this matters and how to handle the edge cases.
FLSA Section 778.105 defines a workweek as:
"A fixed and regularly recurring period of 168 hours — seven consecutive 24-hour periods. It need not coincide with the calendar week, but may begin on any day and at any hour of the day."
This is the period used to determine if overtime is owed (over 40 hours = OT). It's also the period for FLSA recordkeeping requirements.
| Workweek | Common in |
|---|---|
| Sunday 12:00 AM – Saturday 11:59 PM | Most US payrolls; matches calendar week |
| Monday 12:00 AM – Sunday 11:59 PM | Some international companies, healthcare |
| Thursday 12:00 AM – Wednesday 11:59 PM | Restaurants, retail (so weekend hours hit different workweek) |
| Friday 12:00 AM – Thursday 11:59 PM | Some manufacturing operations |
| Sunday 8:00 AM – Sunday 7:59 AM | Operations where shift handoff defines the break |
The strategic reason: to split high-hour weekends across two workweeks.
Example: A restaurant has a non-exempt employee who works Friday night, Saturday lunch, Saturday dinner, and Sunday brunch — totaling 30 hours over a weekend.
Either choice is legal as long as it's consistent. Manipulating workweek boundaries pay period to pay period to avoid overtime is not legal.
Employers can set different workweeks for different establishments, departments, or even individuals — but must do so on a consistent basis. A common setup:
Each group's overtime is calculated within their own workweek. An employer cannot retroactively change workweeks to avoid paying overtime.
An employer can change the workweek definition, but only if:
During a workweek change, you might temporarily have a longer or shorter "transition workweek" — both hours should be paid as OT-eligible if the total exceeds 40.
Overtime is calculated per workweek, not per pay period. This matters for:
A biweekly pay period contains two workweeks. Overtime is calculated separately for each:
You cannot average across the two weeks (40 + 40 = 80, no OT). The 10 hours of OT in week 2 must be paid as OT.
Semi-monthly pay periods (1st-15th, 16th-end of month) often split workweeks across pay periods. This makes overtime tracking tricky:
The FLSA requires employers to keep specific records for each non-exempt employee, including:
Records must be kept for at least 3 years (basic payroll records) or 2 years (records used to compute wages). DOL has authority to audit these without notice.
If an employer hasn't formally defined a workweek, DOL defaults to the calendar week (Sunday 12:00 AM – Saturday 11:59 PM). Some employers think they're "flexible" by not setting one; in reality they've been using the calendar week by default.
"You worked 40 hours this week and 40 hours last week, so no OT" — but if the actual workweeks were 50 and 30, the 50-hour week generates 10 hours of OT regardless of the biweekly average.
This is wage theft and illegal. The DOL has successfully prosecuted employers who shifted workweek boundaries to disrupt overtime accumulation.
Some states (California, Alaska, Nevada) add daily overtime requirements that interact with the workweek definition. In those states, you can owe overtime even if the weekly total is under 40 (because hours over 8 in a day trigger daily OT). See our California overtime guide for the most complex case.
The Hours Calculator handles any workweek configuration. Set your pay period start date to whichever day your workweek begins — Sunday, Monday, or any other day — and the calculator will aggregate the seven consecutive days correctly.
Published May 2026. Spot an error? Email contactus@calculatehours.net.