Date & Time
Time Calculator
Add or subtract two time durations in HH:MM:SS format. Instantly see the result in hours, minutes, and seconds.
Duration 1
Duration 2
Enter durations and click Calculate
Result
—
How is this calculated?
Formula: Convert both durations to seconds, then add or subtract.
Duration in seconds = (Hours × 3600) + (Minutes × 60) + Seconds
Total seconds₁ = H1×3600 + M1×60 + S1
Total seconds₂ = H2×3600 + M2×60 + S2
Result seconds = Total₁ ± Total₂
Hours = floor(Result / 3600)
Minutes = floor((Result % 3600) / 60)
Seconds = Result % 60Calculation history
No calculations yet.
FAQ
Frequently asked questions
How do you add two time durations?
Convert both durations to total seconds, add them together, then convert back to HH:MM:SS. For example, 1:30:00 + 2:45:30 = 5400 + 9930 = 15330 seconds = 4:15:30.
Can the result exceed 24 hours?
Yes. This calculator handles durations (not clock time), so results can exceed 24 hours. For example, 18:00:00 + 10:00:00 = 28:00:00.
How do I convert HH:MM:SS to total seconds?
Multiply hours by 3600, minutes by 60, and add the seconds. Formula: Total seconds = (hours × 3600) + (minutes × 60) + seconds.
What happens if the subtraction result is negative?
If Duration 2 is larger than Duration 1, the result will show as negative. The calculator displays the absolute difference and indicates it is negative.
How do I convert seconds to hours?
Divide total seconds by 3600. For example, 7200 seconds ÷ 3600 = 2 hours. For minutes, divide by 60. These are displayed as decimal values for precision.