Convert hours to seconds
To convert hours to seconds: one hour is 3,600 seconds, so 8 hours is 28,800 seconds. The factor is exact.
In seconds
- Conversion factor Exact.
- 1 hour = 3,600 seconds
- In every unit
- 28,800,000 ms 28,800 s 480 min 8 h 0.33333 day 0.047619 week 0.010952 month 0.00091264 year
- As hours and minutes
- 8:00
- 7.25 decimal hours Multiply the fractional part by 60: 0.25 x 60 = 15 minutes.
- 7 hours 15 minutes (7:15)
- And the other way
- 7:15 is 7.25 decimal hours
- Minutes that convert cleanly
- 15 = 0.25, 30 = 0.50, 45 = 0.75
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 0 | 0 | 30 | 0.5 |
| 5 | 0.0833 | 35 | 0.5833 |
| 10 | 0.1667 | 40 | 0.6667 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.3333 | 50 | 0.8333 |
| 25 | 0.4167 | 55 | 0.9167 |
How the Time Converter works
One hour is exactly 3,600 seconds. That is a fixed convention, not a measurement: 60 seconds to the minute, 60 minutes to the hour, 24 hours to the day and 7 days to the week, with the second as the SI base unit. Leap seconds adjust the clock against the Earth's rotation; they do not change the length of a minute or an hour as a unit, so this factor is exact.
Worked through: 8 h x 3,600 = 28,800 s.
Going the other way, one second is 0.0002777778 hours.
For mental arithmetic: Multiply by 36 and add two zeros.
Multiplying by 3,600 is the direction that turns up in configuration files and cache headers, where every duration is expressed in seconds and a human wants to write hours. An hour is 3,600, a day 86,400, a week 604,800, and a 30-day month 2,592,000. Those four numbers cover most of the TTL values anybody ever types. Getting one wrong by a factor of 60 is a common and expensive configuration bug.
Precision is worth matching to the input. A measurement given as 0.5 h carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.
Time Converter FAQ
How many seconds are in a hour?
3,600. That is exact by convention: the units of the clock are fixed multiples of the second.
What is 8 h in seconds?
28,800 s. Multiply by 3,600: 8 h x 3,600 = 28,800 s.
How do I convert seconds back to hours?
Divide by 3,600, or equivalently multiply by 0.0002777778. One second is 0.0002777778 hours. The two factors are reciprocals, so you only need to remember one of them.
Is there a quick way to do this in my head?
Multiply by 36 and add two zeros. It is close enough for everyday use.
More from the Time Converter
- seconds to hours
- milliseconds to seconds
- minutes to hours
- seconds to milliseconds
- hours to minutes
- seconds to minutes
- minutes to seconds
- hours to days