Across midnight
From 21:45 to 06:15 the next day is 8 hours 30 minutes. The calculator avoids showing a negative result just because the end clock time is smaller than the start clock time.
Breaks and payroll-style time
If a shift is 09:00 to 17:30 with a 30-minute unpaid break, paid time is 8 hours. In decimal hours, 8 hours 15 minutes is 8.25 hours because 15 minutes is 0.25 of an hour.
Seconds, minutes and hours
1 hour = 60 minutes = 3,600 seconds. A duration of 2:45:30 equals 2 hours, 45 minutes and 30 seconds, or 9,930 seconds.
Common mistakes
- Writing 8:30 as 8.30 decimal hours instead of 8.5.
- Forgetting unpaid breaks.
- Mixing elapsed time with clock time.
- Ignoring time zones for travel or remote work.
Use the calculators
- Time Duration Calculator
- Time Card Calculator
- Hours to Minutes Calculator
- Minutes to Seconds Calculator
- Date and Time Formulas
FAQ
Is 8:30 the same as 8.30 hours?
No. 8:30 means 8 hours and 30 minutes, which is 8.5 decimal hours.
How does the calculator handle midnight?
It treats the end time as the next day when the user is calculating a shift or interval that crosses midnight.
Last reviewed: 2026-05-15.