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Time Calculator

Add or subtract any duration in hours, minutes, and seconds from a time of day. The Time Calculator handles midnight wraparound automatically and shows both 12-hour and 24-hour results.

Hours
Minutes
Seconds
:
:

Formula

Result = Start Time ± Duration (wraps around midnight automatically)

Examples:

2:30 PM + 1h 45m 0s = 4:15 PM 11:30 PM + 2h 30m 0s = 2:00 AM (+1 day)

Common Examples

StartOpDurationResult
9:00 AM+8h 0m 0s5:00 PM
2:30 PM+1h 45m 0s4:15 PM
11:30 PM+2h 30m 0s2:00 AM (+1 day)
1:00 AM−2h 0m 0s11:00 PM (−1 day)
6:00 PM−0h 45m 0s5:15 PM

How to Add or Subtract a Duration from a Time

Convert the start time and duration to total seconds, then add or subtract. Convert the result back to HH:MM:SS.

If the result exceeds 24 hours, wrap around midnight. If it goes below 0, wrap back from midnight.

• Add example: 10:30:00 + 2h 45m 30s → 10:30:00 + 9930 s = 13:15:30 (1:15:30 PM)

• Subtract example: 1:00:00 AM − 2h 0m 0s → wraps to 11:00:00 PM the previous day

The calculator shows a (+1 day) or (−1 day) indicator whenever the result crosses midnight.


See also