UnitSnapTime converter
Time measures the duration of events. The SI base unit is the second, defined as exactly 9,192,631,770 periods of the radiation from a specific transition of the caesium-133 atom. Minutes, hours, days, and weeks are fixed multiples of the second: 60 seconds, 3,600 seconds, 86,400 seconds, and 604,800 seconds respectively.
Convert between 8 time units. Pick any two units below; results update as you type.
Popular time conversions
About time units
Unlike most quantities, time units are the same in metric and US customary systems; only subdivisions such as the millisecond use metric prefixes. Months and years are irregular in the calendar, so this converter uses fixed approximations: a month of 30 days and a year of 365 days. Calendar months range from 28 to 31 days.
The Gregorian calendar averages 365.2425 days per year because of leap-year rules. Astronomers often use the Julian year of exactly 365.25 days, which is also the basis of the light-year.
Tips
- Results involving months or years are approximate because real months and years vary in length.
- For long spans such as ages or loan terms, count actual calendar dates rather than multiplying by 30 or 365.
- Decimal hours are not minutes: 1.5 hours is 1 hour 30 minutes, not 1 hour 50 minutes.
All time units
| Unit | Symbol | Value in seconds |
|---|---|---|
| Milliseconds | ms | 1 ms = 0.001 s |
| Seconds | s | 1 s = 1 s |
| Minutes | min | 1 min = 60 s |
| Hours | h | 1 h = 3,600 s |
| Days | d | 1 d = 86,400 s |
| Weeks | wk | 1 wk = 604,800 s |
| Months (30 Days) | mo | 1 mo = 2,592,000 s |
| Years (365 Days) | yr | 1 yr = 31,536,000 s |
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Factors: NIST SP 811 · SI Brochure · NIST Handbook 44 — Updated