Time Calculator
Add or subtract multiple durations — HH:MM:SS, MM:SS or plain seconds
Durations
Add or subtract time durations
01:30:00Add or subtract time durations
+00:45:00Add or subtract time durations
+00:15:3002:30:30
150:30
9030.000
150.5000
About the Time Calculator
This time calculator adds and subtracts durations in hours, minutes and seconds, carrying units correctly so 45 minutes plus 30 minutes gives 1 hour 15 minutes rather than 75. It totals timesheets, session lengths and project hours without manual carrying.
A time calculator exists because time is base 60 and calculators are base 10. Adding 2:45 and 1:30 in a normal calculator gives 4.75, which is not four hours and seventy-five minutes — it is 4:15. Doing it by hand across a timesheet is where errors creep in.
This handles the carrying for you across hours, minutes and seconds, for both addition and subtraction. Totalling a week of shifts, summing billable sessions, or working out how much of an allowance is left all become one entry per row.
Subtraction across boundaries works too, so a task that ran from 23:40 to 00:25 is correctly 45 minutes rather than a negative number. Everything is calculated in your browser.
How to use the Time Calculator
- Choose add or subtract. Pick whether you are totalling durations or finding a difference.
- Enter the first duration. Type hours, minutes and seconds.
- Enter the second duration. Add the next value. Repeat for as many entries as you need.
- Read the total. See the result with units carried correctly.
Time Calculator features
- Add or subtract durations
- Accepts HH:MM:SS and MM:SS
- Carries units correctly, so 45 + 30 minutes gives 1:15:00
- Result also given in plain minutes and seconds
- Copy the result
- Runs in your browser; nothing is uploaded
Frequently asked questions
What can it add up?
Durations — lengths of time rather than clock times. Session lengths, timesheet entries, track lengths, billed hours: anything where you need a total and the units have to carry properly.
Why not just add the numbers?
Because time is not decimal. 45 minutes plus 30 minutes is 1 hour 15 minutes, not 75 of anything useful, and doing that by hand across a dozen timesheet rows is where the errors creep in.
Does it convert between time zones?
No. This works on durations, not on clock times in particular places, so there is no zone or daylight-saving handling involved.
Why is the answer also shown in minutes and seconds?
Because billing and reporting usually want a single unit. A total of 1:15:00 is 75 minutes or 4,500 seconds, and having all three saves converting by hand.
Can I subtract as well as add?
Yes, switch the operation. Subtracting is how you get the remaining time against a budgeted total, or the gap between two recorded durations.