Add or subtract
Pick + to combine two durations or − to find the difference. Negative results are shown with a minus sign.
Time calculators
Time Calculator
Add or subtract durations in hours, minutes, and seconds.
Complete guide
How to use Time Calculator
Enter two durations in hours, minutes, and seconds, choose add or subtract, and the calculator normalizes the result (75 minutes becomes 1h 15m) and shows it in H:MM:SS plus total seconds.
Useful for timesheets, shift lengths, cooking, video editing, and any task where you need to combine elapsed times.
Automatic normalizing
Enter any values - the calculator rolls 90 seconds into 1m 30s and 80 minutes into 1h 20m for you.
Multiple output formats
Results appear as a readable ‘3h 45m 0s’ and as ‘03:45:00’, plus the raw total in seconds.
Answers
Time Calculator FAQs
How do I add time durations?
Enter the hours, minutes, and seconds for each value, select Add (+), and the result is normalized automatically.
Can I get a negative result?
Yes. If the subtraction goes below zero (e.g. 1:00 − 2:30), the result is shown with a minus sign.
Is this a clock or duration calculator?
It works with durations. To find the gap between two times of day, use the Date Difference Calculator.
How many seconds are in an hour?
3,600 seconds - 60 minutes times 60 seconds.
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Calculation method and limitations
Formula or method
Convert each duration to seconds: hours x 3600 + minutes x 60 + seconds. Add or subtract, then normalize back to hours, minutes and seconds.
Worked example
1 hour 45 minutes plus 2 hours 30 minutes equals 4 hours 15 minutes, or 15,300 seconds.
Assumptions and limitations
Durations are not times of day. This operation does not account for time zones, calendar dates or daylight-saving transitions.
Important: Check the assumptions and inputs before relying on this estimate for an important decision.
Editorial note: Review the input definitions, units and assumptions before relying on results. For corrections, contact FormatNest with your inputs and expected result.