Three time calculations in one place
Hours and Minutes Calculator
Add or subtract durations, find the time between two clock times, or add a duration to a starting time. Results include hours, minutes, seconds and decimal hours.
Choose a calculation
Use a minus sign on any row you want to subtract. Minutes and seconds stay between 0 and 59.
Find elapsed time
If the end is earlier than the start, it is treated as the following day.
Move a clock time
What this hours calculator can do
The duration mode combines positive and negative blocks of time without treating them as clock times. The elapsed-time mode subtracts a start time from an end time and can remove an unpaid break. The clock mode moves a starting time forward or backward and reports when the result crosses a day boundary. This is a time-duration tool, not an algebra, angle or degree calculator.
How hours and minutes are calculated
ClockSlate converts each value to an integer number of seconds, performs the calculation, then converts the result back to hours, minutes and seconds. Decimal hours are the total seconds divided by 3,600.
Examples
- 1 hour 30 minutes plus 2 hours 45 minutes = 4 hours 15 minutes, or 4.25 decimal hours.
- 9:00 AM to 5:30 PM minus 30 minutes = 8 hours worked.
- 10:30 PM plus 8 hours 30 minutes = 7:00 AM the next day.
Frequently asked questions
Can the total be negative?
Yes. If the durations you subtract are larger than those you add, the result displays a minus sign.
What happens when a time crosses midnight?
Elapsed-time calculations treat an earlier end as the following day. Clock-time calculations show a day offset such as “next day” or “previous day.”
Is 1 hour 30 minutes equal to 1.30 hours?
No. Thirty minutes is half an hour, so 1 hour 30 minutes equals 1.50 decimal hours.