How to Calculate Overtime Across Pay Periods (Free Tool)

Workweek vs pay period: what is the difference?

A workweek is a fixed, repeating 168-hour period used to count overtime. A pay period is how often you are paid. They can start on different days and overlap.

Why is overtime calculated by workweek?

The FLSA treats each workweek separately; you cannot average a 30-hour week and a 50-hour week to 40 and 40 (29 CFR 778.104). The two-week example gives 10.00 overtime hours.

Step-by-Step calculation

Find the workweek start day and time.
Place each shift in its workweek, splitting shifts that cross the start of a new workweek.
Subtract unpaid breaks.
In each workweek the hours after the 40th are overtime.
Multiply overtime hours by the premium (half the regular rate).
Allocate hours to pay periods.

Example: semi-monthly pay period splits a workweek

Ana works 54.00 hours from Monday Oct 26 to Saturday Oct 31. 40.00 are regular and 14.00 are overtime. All the hours are worked in the Oct 16-31 period, but the workweek ends Sunday Nov 1, so under 29 CFR 778.106 the overtime is generally due on the payday for the Nov 1-15 period.

How to allocate overtime to payroll

Pay straight time for the period in which hours were worked. Pay the overtime premium with the period in which the workweek ends. If your payroll system pays everything in the period worked, check that the total owed is still correct.

Common errors

Dividing 40 hours by the number of days in a pay period.
Averaging two workweeks.
Using the calendar week when payroll uses a different workweek.
Forgetting that a shift crossing midnight on the workweek boundary belongs to both weeks.
Forgetting unpaid break deductions.

Federal rule and state-specific considerations

This guide covers the federal weekly rule. States such as California add daily overtime and double time; employers may also follow union contracts or longer rules. Check your state labor department.

Why does the workweek start day matter?

Changing the start day can change who has overtime. Five 10-hour days from Saturday to Wednesday are 50 hours in one Saturday-start workweek, which is 10 hours of overtime, but 20 and 30 hours in two Monday-start workweeks, which is none. The employer fixes the workweek, it can begin on any day and hour, and it can be changed only if the change is meant to be permanent and is not made to avoid overtime (29 CFR 778.105).

How should you record the method?

Write down the workweek start day and time, the pay-period type and the way overtime is allocated, and keep it with the payroll records. If an employee or an auditor asks how a figure was reached, the same steps can then be repeated. This guide is general information about the federal weekly rule, not legal advice.

Workweek-boundary overtime checkerSet the workweek start, enter shifts that cross a pay-period boundary and see overtime by workweek and by pay period.

Common questions

Is overtime calculated by pay period or workweek?

By workweek. Under the Fair Labor Standards Act each workweek stands on its own: a fixed, repeating period of 168 hours (seven 24-hour days) that does not have to match the calendar week or the pay period (29 CFR 778.104 and 778.105). Pay frequency changes when you are paid, not when overtime starts.

How do you calculate overtime when a pay period ends midweek?

Put every hour in its fixed workweek first. In each workweek, hours after the 40th are overtime, in the order they were worked. Then allocate: the overtime premium for a split workweek is generally due on the regular payday for the pay period in which that workweek ends (29 CFR 778.106). Example: Ana works Mon-Fri 10 hours plus 4 on Saturday, a 54.00-hour week from Oct 26 to Nov 1. The 14.00 overtime hours are worked in the Oct 16-31 period but the week ends on Nov 1, so they are due with the Nov 1-15 period's payday.

Can overtime hours be averaged across two workweeks?

No. If someone works 30 hours one week and 50 the next, the 10 hours over 40 in the second week are overtime even though the two weeks average 40 (29 CFR 778.104). The tool shows this: in its calculation for 80.00 hours over two weeks of 30 and 50, overtime is 10.00 hours, not zero.

How do you calculate overtime for semi-monthly payroll?

Semi-monthly periods (1st-15th and 16th-end of month) have different lengths and rarely line up with workweeks, so never divide 40 hours by period length. Compute overtime for each fixed workweek, then assign the hours and the overtime to the periods as described above. The "wrongly pro-rated" column in the tool shows how far off a pro-rated threshold can be.

What if a workweek crosses two pay periods (a workweek spans two pay periods)?

Count the whole workweek as one unit for overtime. The straight-time hours belong to the pay periods in which they were worked, and the overtime premium is generally due on the payday for the period in which the workweek ends. The tool marks such weeks as "split" and shows both views. Employers sometimes pay differently, and state rules can differ.

Does biweekly payroll change the 40-hour overtime rule?

No. Federal overtime is still over 40 hours in each workweek, not over 80 in two weeks. The main exceptions are hospitals and residential care facilities that use the 8-and-80 system (see the 8 and 80 calculator) and certain public-safety work periods.

How do I set the workweek start day for overtime?

The employer chooses a fixed, recurring 168-hour workweek that can begin on any day and hour, and it stays the same regardless of schedule. It can be changed only if the change is meant to be permanent and is not made to avoid overtime (29 CFR 778.105). Use the start day your payroll actually uses; if you are an employee, ask payroll or check your policy. This is general information, not legal advice.

Sources

Reviewed on 25 Oct 2026 against the published sources below. Laws and prices change, so check the current position before you rely on a figure.

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This guide is general information, not legal, financial or religious advice. Figures are estimates worked out from the sources above and may differ from what applies to you. See the disclaimer. Found a mistake? Tell us.