Time Calculator: Add and Subtract Time
Enter any number of durations and choose to add or subtract each one. The total is shown in hours, minutes and seconds and as decimal hours.
Result
- Decimal hours
- 4.25 hours
- Total minutes
- 255 minutes
- Total seconds
- 15,300 seconds
- Days, hours, minutes, seconds
- 0 d 4 h 15 min 0 s
- Average of the entries
- 2:07:30
Formula
- Total seconds = Σ (hours × 3,600 + minutes × 60 + seconds)
- Hours = total seconds ÷ 3,600, minutes = remainder ÷ 60
How the Time Calculator works
Time is counted in base 60, so it cannot be added like ordinary decimals. The reliable method is to convert every duration to seconds, add or subtract, and convert the total back to hours, minutes and seconds.
Minutes and seconds above 59 are accepted. Entering 90 minutes is the same as 1 hour 30 minutes.
Worked example
2 h 45 min plus 1 h 30 min: 2 × 3,600 + 45 × 60 = 9,900 seconds, and 1 × 3,600 + 30 × 60 = 5,400 seconds. The total of 15,300 seconds is 4:15:00, or 4.25 hours.
Frequently asked questions
How do I add hours and minutes?
Add the minutes first. If they reach 60 or more, carry one hour for every 60 minutes. Then add the hours. 2:45 plus 1:30 is 3 hours and 75 minutes, which is 4:15.
How do I find the average of several times?
Convert each to seconds, add them and divide by the count. The calculator shows this average on the last line.
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Calculations run in your browser and nothing you enter is sent to a server. Results are provided for general information. Check critical figures independently before relying on them.