Date & Time
Age, duration & timezone calculators
Overnight Hours Calculator (cross-midnight shifts)
Calculate the hours of an overnight shift that crosses midnight — like 22:00 → 06:00 for a night, graveyard or hospital shift — without the negative-number bug plain calculators produce. Enter the start and end times, turn on Overnight, and the calculator adds 24 hours before subtracting so the result reads 8 hours, not −16. It returns the duration as H:MM (8h 00m), total minutes (480) and decimal hours (8.0), and you can subtract an unpaid break such as a 30-minute meal period. The math runs purely on clock minutes, so the answer is stable regardless of your time zone; a real duration across a daylight-saving change needs full calendar dates instead. Everything is computed in your browser and nothing leaves your device.
Overnight = add 24 hours to the end when it is earlier than the start
- 22:00 → 06:00 = 8h 00m = 480 minutes = 8.0 decimal hours (not −16h)
- Subtract an unpaid break; decimal hours ready for the timesheet
Frequently asked questions
How many hours is a 22:00 to 06:00 shift?
Eight hours. The interval crosses midnight, so turning on Overnight adds 24 hours to the end: 06:00 becomes 30:00, minus 22:00, is 8 hours (480 minutes). Without the overnight flag a plain subtraction would wrongly give −16 hours.
Why do I need the Overnight toggle?
When the end time is earlier than the start on the clock, the interval must run into the next day. The Overnight toggle tells the calculator to add 24 hours before subtracting, which is the fix for the classic cross-midnight negative-duration bug.