Shift Differential Hours Calculator
A shift differential pays extra for hours worked in a defined night or evening window. To apply it you first need to know how many of a shift's hours fall inside that window. This calculator takes your shift start and end, the differential window, your base hourly rate, and the differential percentage, then splits the shift into regular and differential hours and totals the extra differential pay. It handles shifts and windows that cross midnight. Differential rates are set by employer policy or contract, so enter the figures that apply to you.
Shift differential formula
Convert all times to minutes; unwrap any that cross midnight by adding 1,440
Differential minutes = overlap of shift interval with window interval
Differential hours = differential minutes / 60
Regular hours = total shift hours - differential hours
Differential pay = differential hours * base rate * (percentage / 100)
Total pay = (total hours * base rate) + differential pay
The overlap is measured against the window repeated across two days so a window like 6:00 PM to 6:00 AM is matched correctly for overnight shifts.
Shift differential context
- Shift differentials reward evening, night, or weekend work and are set by employer policy or contract.
- The Fair Labor Standards Act does not require private employers to pay shift differentials.
- When paid, differentials are generally included in the regular rate used to compute overtime.
- Federal government employees receive statutory night pay differentials under separate rules.
- Common night windows run roughly 6:00 PM to 6:00 AM, but yours may differ; enter your own.
Shift differential hours: frequently asked questions
What is a shift differential?
A shift differential is extra pay for working less desirable hours, usually evenings or nights. It is commonly expressed as a percentage of base pay (for example 10%) or a flat dollar amount per hour. Federal law does not require shift differentials for most private employers; they are set by employer policy or contract.
How are differential hours counted?
The calculator counts how many of the shift's hours fall inside the differential window (for example 6:00 PM to 6:00 AM). Hours inside the window earn the differential; hours outside it are paid at the base rate. This calculator measures the overlap between your shift and the differential window to the hour.
Is shift differential pay required by law?
For most private-sector employees there is no federal requirement to pay a night or shift differential; the Fair Labor Standards Act does not mandate it. Federal government employees do receive statutory night differentials under separate rules. Private differentials come from employer policy, union contracts, or state law.
Does the differential affect overtime pay?
It can. Under the Fair Labor Standards Act, shift differentials are generally part of the regular rate of pay used to compute overtime for non-exempt workers. This calculator estimates straight-time differential pay only; consult payroll for the overtime regular-rate computation.
How is the differential amount calculated?
Multiply the base hourly rate by the differential percentage to get the extra per-hour amount, then multiply by the number of differential hours. For example, a $20 base rate with a 10% differential is $2.00 extra per hour; over 8 differential hours that is $16.00 in differential pay.
Official sources
- U.S. Department of Labor: Fair Labor Standards Act (Wage and Hour Division).
- U.S. Office of Personnel Management: Pay and Leave.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.