Time Duration Calculator
Add or subtract two lengths of time in hours, minutes, and seconds.
Time Duration Calculator calculates in your browser.
Add or subtract lengths of time
Totalling the length of two videos, adding up time spent on a task, or taking a break off a shift: enter two durations in hours, minutes, and seconds, choose Add or Subtract, and the result appears with totals in minutes, seconds, and decimal hours. These are lengths of time, not times of day — for the time between two clock times, use the Hours Between Times Calculator.
How to use the Time Duration Calculator
- Enter the first duration. Leave any box empty for 0.
- Choose Add or Subtract.
- Enter the second duration and read the result. Copy Result copies a line such as “1h 45m 0s + 2h 30m 0s = 4 hours 15 minutes”.
The method
seconds = hours × 3,600 + minutes × 60 + seconds
result = first duration ± second duration
then split back into hours, minutes, and seconds
Time counts in 60s, so adding durations is like adding numbers with an unusual carry: every 60 seconds make a minute and every 60 minutes make an hour. The calculator converts both durations to seconds, adds or subtracts them, and converts the answer back, so carrying and borrowing are always exact.
| Calculation | Result | Decimal hours |
|---|---|---|
| 1h 45m 0s + 2h 30m 0s | 4 hours 15 minutes | 4.25 hours |
| 5h 0m 0s − 1h 35m 30s | 3 hours 24 minutes 30 seconds | ≈ 3.41 hours |
| 0h 45m 50s + 0h 30m 20s | 1 hour 16 minutes 10 seconds | ≈ 1.27 hours |
| 1h 0m 0s − 2h 30m 0s | -1 hour 30 minutes | -1.5 hours |
| 2h 15m 0s + 0h 50m 45s | 3 hours 5 minutes 45 seconds | ≈ 3.1 hours |
Calculated on your device
- The calculation runs in your browser as you type; nothing is sent to a server.
- The times you enter and the results are not sent to Looty Tools or stored.
- The calculator area is masked from session-recording analytics, so what you enter isn’t captured in recordings.
Limitations
- Two durations at a time. For more, enter the result as the first duration and add the next one.
- Whole numbers only — enter 1.5 hours as 1 hour 30 minutes. Each box takes up to 1,000,000.
- Results are shown in hours rather than days: 30 hours stays 30 hours.
- When the second duration is longer, the difference is shown as a negative number.
Related calculators
Guides
- Add Hours and MinutesAdd lengths of time by hand with carrying, total a list of durations, and add times in a spreadsheet without the total wrapping past 24 hours.
- Subtract DurationsSubtract one length of time from another by borrowing minutes and hours, handle negative results, and take a break off a shift total.
- Hours, Minutes, SecondsConvert durations between hours, minutes, and seconds, split a number of seconds into hours, minutes, and seconds, and turn decimal hours into minutes.
Time Duration Calculator FAQ
- How do I add hours and minutes?
- Add the hours and the minutes separately, then carry every 60 minutes into an hour: 1h 45m + 2h 30m is 3h 75m, which is 4h 15m. The calculator does the carrying for you, including seconds.
- How do I subtract one duration from another?
- Choose Subtract. When there aren’t enough minutes or seconds to take away, one hour or minute is borrowed: 5h 0m − 1h 35m is 3h 25m.
- What if the result is negative?
- It is shown with a minus sign, along with a note saying how much longer the second duration is. 1h − 2h 30m gives −1 hour 30 minutes.
- Can I type 90 minutes instead of 1 hour 30 minutes?
- Yes. Minutes and seconds of 60 or more are carried over automatically, and a note says so.
- How is this different from the Hours Between Times Calculator?
- This calculator works with lengths of time, such as a 45-minute meeting or a 2-hour film. Hours Between Times works with clock times, such as 9:00 AM to 5:30 PM.
- Can I add more than two durations?
- Not in one step. Add the first two, then enter the result as the first duration and add the next one.
- Can I enter fractions, like 1.5 hours?
- No — each box takes a whole number. Enter 1.5 hours as 1 hour and 30 minutes.
- Are the dates and times I enter sent anywhere?
- No. The calculation runs in your browser as you type. The dates and times you enter and the results are not sent to Looty Tools or stored, and the calculator area is masked from session-recording analytics. Refreshing the page clears it.
