Multiply by 3,600
An hour is 60 minutes and a minute is 60 seconds, so one hour is 60 × 60 = 3,600 seconds exactly. To go the other way, divide by 3,600. A minute is 60 seconds by definition, which makes every step in this chain exact rather than approximate.
Common values
| Hours | Minutes | Seconds |
|---|---|---|
| 0.25 h | 15 min | 900 s |
| 0.5 h | 30 min | 1,800 s |
| 1 h | 60 min | 3,600 s |
| 1.5 h | 90 min | 5,400 s |
| 2 h | 120 min | 7,200 s |
| 8 h | 480 min | 28,800 s |
| 24 h | 1,440 min | 86,400 s |
A full day is 86,400 seconds — a useful anchor, since it is also the number Unix time counts up each calendar day.
Decimal hours are base 10, the clock is base 60
- 0.5 h is 30 minutes, not 50. Half of 60 is 30. The decimal fraction is a share of an hour, not a minute count.
- To split seconds into h:m:s, divide by 3,600 for whole hours, take the remainder over 60 for minutes, and the last remainder is seconds. 7,325 s is 2:02:05.
- Small times need decimals. One second is 0.000278 of an hour, so rounding to two places loses it entirely.
Common questions
How many seconds are in an hour?
Exactly 3,600. An hour is 60 minutes and each minute is 60 seconds, so 60 times 60 gives 3,600 seconds. The relationship is fixed, with no rounding.
How many seconds is 2.5 hours?
9,000 seconds. Multiply 2.5 by 3,600. As a check, 2 hours is 7,200 seconds and half an hour is 1,800, which add to 9,000.
Is 1.5 hours the same as 1 hour 50 minutes?
No. The decimal 0.5 of an hour is 30 minutes, not 50, so 1.5 hours is 1 hour 30 minutes, or 5,400 seconds. Decimal hours run on base 10 while the clock runs on base 60, which is the usual trap.
