Add or subtract durations to get a total in hours, minutes and seconds.
This time calculator works with durations and clock times. Use it to add up hours and minutes, find how long there is between two times, or shift a clock time forward or backward by a set amount. Everything runs in your browser.
Pick a mode at the top. In Add / Subtract, enter each duration and choose + or −, then read the total. In Time Between, enter a start and end time (turn on “next day” if it passes midnight). In Time ± Duration, set a base time and add or subtract hours, minutes and seconds.
Each duration is converted to seconds, summed with its sign, then formatted back into hours : minutes : seconds. Clock times are treated as seconds since midnight; crossing midnight adds or subtracts whole days, shown as +1 day or −1 day.
Decimal hours (for example 2.5 h) are useful for pay and time sheets, while h:m:s is best for everyday durations. Minutes and seconds above 59 are carried over automatically, so you can type 90 minutes and it becomes 1 h 30 m.
Use Add / Subtract mode, add a row for each duration, and the running total updates instantly with proper carrying.
Use Time Between, enter the start and end times, and enable “next day” if the end is after midnight.
It expresses the duration as a single number of hours, e.g. 1 h 45 m = 1.75 h, which is convenient for billing.
Yes — use Time ± Duration, choose Subtract, and the result shows the new clock time and any day offset.