Add Time Calculator
Choose whether the first value is a time of day on a 24-hour clock or a duration, then enter the time to add.
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Formula
total seconds = (h1 × 3600 + m1 × 60 + s1) + (h2 × 3600 + m2 × 60 + s2)
For a time of day, the clock reading is total seconds mod 86400 and the days later are floor(total ÷ 86400). For durations the hours are not wrapped.
Worked example
9:45:30 is 35,130 seconds and 2 h 30 min 45 s is 9,045 seconds. The total is 44,175 seconds: 12 hours (43,200) plus 975 seconds (16 minutes 15 seconds), so the answer is 12:16:15.
Frequently asked questions
How do I add hours and minutes to a time?
Convert both to seconds, add them and convert back. 9:45:30 plus 2 hours 30 minutes 45 seconds is 35,130 + 9,045 = 44,175 seconds, which is 12:16:15.
What happens when the total passes midnight?
In time of day mode the clock wraps around and the days later count goes up. 22:30:00 plus 3 hours 45 minutes is 02:15:00, 1 day later.
How do I add two durations together?
Choose the duration mode so hours are not limited to 23. 5:50:00 plus 3:25:30 is 9:15:30, and 20:00:00 plus 10:00:00 is 30:00:00.
Can I subtract time with this calculator?
No, it only adds. To find a gap between two times of day, subtract the earlier time in seconds from the later one.