Time Converter: Units, Formulas, and Examples
Convert durations between seconds, minutes, hours, days, weeks, and Julian years.
How to convert time
Converted value = input value × source factor ÷ target factor. Factors express each unit in seconds.
Keep the source and target definitions consistent, apply the conversion to the original value, and round the final answer to the precision needed for your calculation.
Understanding time units
These units represent fixed durations. One minute has 60 seconds, one hour has 60 minutes, and one day here is exactly 24 hours. A Julian year is exactly 365.25 days.
| Unit | In s |
|---|---|
| Seconds (s) | 1 |
| Milliseconds (ms) | 0.001 |
| Microseconds (µs) | 0.000001 |
| Nanoseconds (ns) | 0.000000001 |
| Minutes (min) | 60 |
| Hours (h) | 3,600 |
| Days (d) | 86,400 |
| Weeks (wk) | 604,800 |
| Julian years (365.25 days) (Julian yr) | 31,557,600 |
Worked time examples
1 hour = 60 minutes = 3,600 seconds. 2 weeks = 14 days = 336 hours.
Frequently asked questions
Which definitions should I use?
Calendar months have different lengths and calendar years may have 365 or 366 days. Use a date calculator for elapsed time between calendar dates. Daylight-saving changes and leap seconds are not part of these fixed-duration conversions.
Why do displayed results sometimes differ slightly?
Intermediate arithmetic uses browser floating-point numbers. Display rounding and the precision of an original measurement can affect the last digits. The unit conversion does not improve the accuracy of a measured value.
Does converting back recover the original value?
Using the unrounded result normally recovers the original quantity within floating-point precision. Copying a rounded number can introduce a small difference.
How are the unit definitions documented?
For physical unit definitions and conversion factors, see the NIST conversion reference.