A night shift that starts at 10:00 PM and ends at 6:30 AM gives a negative number if you subtract the times directly. The fix is simple: when a shift ends earlier on the clock than it started, it ended the next day, so add 24 hours to the end time before you subtract.
The add-24-hours rule
- Write both times on a 24-hour clock: 10:00 PM is 22:00 and 6:30 AM is 06:30.
- The end time (06:30) is earlier than the start time (22:00), so add 24 hours to the end: 06:30 becomes 30:30.
- Subtract: 30:30 − 22:00 = 8 hours 30 minutes.
- Subtract unpaid breaks. With a 30-minute unpaid meal break, the shift pays 8 hours.
In minutes the same calculation is (390 + 1,440) − 1,320 = 510 minutes, minus 30 = 480 minutes.
Common night shifts
| Shift | Length | With 30-minute unpaid break | Decimal hours paid |
|---|---|---|---|
| 11:00 PM to 7:00 AM | 8h 00m | 7h 30m | 7.50 |
| 10:00 PM to 6:30 AM | 8h 30m | 8h 00m | 8.00 |
| 7:00 PM to 7:30 AM | 12h 30m | 12h 00m | 12.00 |
| 6:00 PM to 6:00 AM | 12h 00m | 11h 30m | 11.50 |
| 3:00 PM to 1:00 AM | 10h 00m | 9h 30m | 9.50 |
What about a shift that starts and ends at the same time?
A 7:00 AM to 7:00 AM entry could mean zero hours or a full 24-hour shift. Good calculators ask instead of guessing. If you really worked 24 hours, enter it as two shifts, for example 7:00 AM to 7:00 PM and 7:00 PM to 7:00 AM.
Daylight saving time
Clock arithmetic assumes every hour exists exactly once. On the night clocks spring forward, a shift that crosses the change is one hour shorter in real time than the clock times suggest. On the night clocks fall back, it is one hour longer. If you work those nights, check how your employer records the hour.
Which day and week do the hours belong to?
Most time cards put a night shift on the day it started, which is what the time card calculator does. For overtime, the U.S. Department of Labor describes a workweek as a fixed, recurring 168-hour period that can start on any day and at any hour, and each workweek stands alone. Hours are generally counted in the workweek in which they are worked. A shift that crosses the moment your workweek ends may be split between two weeks. Ask payroll where your workweek starts and how they assign overnight shifts.
Night differentials
Some employers pay extra for hours worked at night, often for hours inside a set window such as 10:00 PM to 6:00 AM. Federal law does not require a night differential; it comes from employer policy or a contract. To work out how many of your hours fall inside the window, use the shift hours calculator and turn on the night window option.
Tools for night shifts
- Shift hours calculator: paid hours for one shift, a timeline, night-window hours, and the time your shift ends.
- Time card calculator: a full week of shifts, including overnight ones, with overtime.
- Time calculator: the time between any two clock times.
Sources
About this guide. Written for US employees as general information, not legal or tax advice. Rules can differ by state, employer, and contract. See our methodology and disclaimer.