Overnight Shift Calculator
Standard Formula
Duration = (End Hour + 24 - Start Hour) % 24
Handles graveyard and third-shift spans that cross midnight seamlessly.
How Overnight Shift Calculator Works?
The Overnight Shift Calculator works by adding 24 hours to the end time when the shift crosses midnight, then subtracting the start time to get the shift length.
1Enter the start hour
Use 24-hour format: 21 = 9:00 PM.
2Enter the end hour
Use 24-hour format: 6 = 6:00 AM the next morning.
3Enter the hourly rate
Type the base wage, $26.00 by default.
4Read duration and pay
(6 + 24 − 21) = 9.00 hours, paying $234.00 at $26.00 per hour.
Overnight Shift Calculator Formula
The Overnight Shift Calculator formula is Duration = (End Hour + 24 − Start Hour) mod 24.
Shift duration
Duration = (End + 24 − Start) mod 24
Shift pay
Pay = Duration × Rate
- Start, End
- Clock hours in 24-hour decimal format.
- mod 24
- Keeps the result between 0 and 24 hours.
- Duration
- Elapsed hours of the shift.
Worked example: 10:30 PM to 7:00 AM
Start = 22.5, End = 7. Duration = (7 + 24 − 22.5) mod 24 = 8.5 hours (8h 30m).
Overnight Shift Calculator Conversion Table
The Overnight Shift Calculator conversion table converts 8 overnight start and end times into elapsed hours and pay at $26.00 per hour.
| Start | End | Duration | Duration (h:m) | Hours Before Midnight | Shift Pay |
|---|---|---|---|---|---|
| 6:00 PM | 2:00 AM | 8.00 hrs | 8h 0m | 6.00 hrs | $208.00 |
| 7:00 PM | 7:00 AM | 12.00 hrs | 12h 0m | 5.00 hrs | $312.00 |
| 8:00 PM | 4:00 AM | 8.00 hrs | 8h 0m | 4.00 hrs | $208.00 |
| 9:00 PM | 6:00 AM | 9.00 hrs | 9h 0m | 3.00 hrs | $234.00 |
| 10:00 PM | 6:00 AM | 8.00 hrs | 8h 0m | 2.00 hrs | $208.00 |
| 10:30 PM | 7:00 AM | 8.50 hrs | 8h 30m | 1.50 hrs | $221.00 |
| 11:00 PM | 7:00 AM | 8.00 hrs | 8h 0m | 1.00 hrs | $208.00 |
| 11:00 PM | 11:00 AM | 12.00 hrs | 12h 0m | 1.00 hrs | $312.00 |
What is Overnight Shift Calculator?
An Overnight Shift Calculator is a tool that measures shift length when work starts on one calendar day and ends on the next.
Simple subtraction fails across midnight: 6 − 21 = −15. Adding 24 hours fixes the result: 6 + 24 − 21 = 9.
Overnight shifts that cross the workweek cutoff split their hours between 2 workweeks. A shift that crosses a daylight saving change gains or loses 1 hour of real time.
What are the uses of Overnight Shift Calculator?
There are 4 main uses of the Overnight Shift Calculator.
Graveyard shifts
Night workers compute the length of a third shift.
Security and healthcare
Guards and night nurses total cross-midnight hours.
Night differential windows
Workers count hours inside a night premium window.
Payroll entry
Clerks enter correct durations for shifts that end the next day.