Convert milliseconds to seconds
To convert milliseconds to seconds: one millisecond is 0.001 seconds, so 500 milliseconds is 0.5 seconds. The factor is exact.
In seconds
- Conversion factor Exact.
- 1 millisecond = 0.001 seconds
- In every unit
- 500 ms 0.5 s 0.0083333 min 0.00013889 h 0.000005787 day 8.2672e-7 week 1.9013e-7 month 1.5844e-8 year
- As hours and minutes
- 0:00
- 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 millisecond is exactly 0.001 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: 500 ms x 0.001 = 0.5 s.
Going the other way, one second is 1,000 milliseconds.
For mental arithmetic: Move the decimal point three places left.
Divide by a thousand, which is the one decimal factor in the time dimension: the SI prefixes apply below the second and stop above it. This conversion is almost entirely a software one: timestamps, durations and performance budgets are kept in milliseconds because that is what the clock APIs return, and read in seconds because that is what a person understands. The 1,000 versus 1,000,000 distinction matters too: JavaScript works in milliseconds and most Unix tooling in seconds, which is why timestamps are so often out by a factor of a thousand.
Precision is worth matching to the input. A measurement given as 1 ms 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 millisecond?
0.001. That is exact by convention: the units of the clock are fixed multiples of the second.
What is 500 ms in seconds?
0.5 s. Multiply by 0.001: 500 ms x 0.001 = 0.5 s.
How do I convert seconds back to milliseconds?
Divide by 0.001, or equivalently multiply by 1,000. One second is 1,000 milliseconds. 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?
Move the decimal point three places left. It is close enough for everyday use.
More from the Time Converter
- seconds to milliseconds
- hours to seconds
- seconds to hours
- seconds to minutes
- minutes to seconds
- years to seconds
- days to weeks
- minutes to hours