Time duration calculator
Hours and minutes between two times (overnight shifts included), add or subtract time, total a timesheet and convert decimal hours to h:mm.
Time calculation
Enter a start and end time to get the duration in hours and minutes and in decimal hours. A shift from 08:30 to 17:15 is 8 h 45 min; minus a 30-minute unpaid break it is 8 h 15 min, or 8.25 hours. If the end time is earlier than the start, the calculator assumes the end is on the next day, so 22:00 to 06:30 is an 8 h 30 min night shift.
Other modes add or subtract hours and minutes from a clock time (21:30 plus 3 h 45 min is 01:15 the next day), add up a list of durations for a timesheet, and convert between decimal hours and hours:minutes. The timesheet accepts 7:45, 7h 45m, 45m, decimal hours like 7.5 and whole clock ranges like 09:00-17:30 on each line; add an hourly rate to see the pay.
Decimal hours = hours + minutes ÷ 60. Payroll systems use them because they multiply easily: 7 h 45 min is 7.75 hours, and 0.1 hours is 6 minutes, not 10. Times can be typed on the 24-hour clock or with am/pm (9:30 pm = 21:30). The calculator counts clock time and does not adjust for daylight-saving changes during the night.
How to use it
- Choose a mode: time between two times, add or subtract time, add up a list, or convert decimal hours.
- Type the times (08:30 or 8:30 am) or durations; for a timesheet put one entry per line.
- Enter a break or an hourly rate if you need them.
- Read the result in hours and minutes and in decimal hours, and copy it into your timesheet.
Frequently asked questions
How do I calculate hours worked between two times?
Subtract the start from the end, then take off any unpaid break. From 08:30 to 17:15 is 8 h 45 min; with a 30-minute break it is 8 h 15 min. Convert the minutes to decimal by dividing by 60: 8.25 hours.
How do I calculate an overnight shift?
Add 24 hours to the end time when it is earlier than the start. 22:00 to 06:30 is (6:30 + 24:00) − 22:00 = 8 h 30 min. The calculator does this automatically and marks the result as crossing midnight.
How do I convert minutes to decimal hours?
Divide the minutes by 60: 15 min = 0.25 h, 30 min = 0.5 h, 45 min = 0.75 h, 20 min ≈ 0.33 h. To go back, multiply the decimal part by 60: 0.4 h × 60 = 24 minutes.
Why does my timesheet show 7.30 when I worked 7 h 30 min?
It should show 7.50. Writing 7 h 30 min as 7.30 is a common payroll mistake that loses 12 minutes of pay (7.30 hours is 7 h 18 min). Use the convert mode to check.
Does it handle daylight saving time?
No. It measures clock time, so a night shift during which the clocks change will show one hour more or less than the time actually worked. Adjust by one hour on those two nights a year.
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