Unix timestamp calculator
Unix time counts seconds since 1 January 1970 UTC, ignoring leap seconds. It is the reference clock of nearly all computing.
Time of day in UTC
15:06:40
- Days since the epoch
- 20 254
- Approximate year
- 2025
- Years since the epoch
- 55.455 292
- Weeks since the epoch
- 2893.429
- In milliseconds
- 1 750 000 000 000
- Years until the 32-bit rollover
- 12.5958
- Seconds until the rollover
- 397 483 647
Show the working
- Unix timestamp = 1 750 000 000
- Days since the epoch = floor(1 750 000 000 / 86400) = 20 254
- Time of day in UTC = mod(1 750 000 000, 86400) = 54 400
- Years since the epoch = 1 750 000 000 / 31556952 = 55.4553
- Approximate year = 1970 + floor(55.4553) = 2025
- Weeks since the epoch = 20 254 / 7 = 2893.43
- In milliseconds = 1 750 000 000 * 1000 = 1 750 000 000 000
- Seconds until the rollover = 2147483647 - 1 750 000 000 = 397 484 000
- Years until the 32-bit rollover = 397 484 000 / 31556952 = 12.5958
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- Unix time = seconds since 1970-01-01T00:00:00Z, excluding leap seconds
- a signed 32-bit counter overflows at 2 147 483 647, which is 19 January 2038
Unix time deliberately ignores leap seconds, so it is not a count of real elapsed SI seconds since 1970 — it is off by the number of leap seconds inserted.
The approximate year is derived from the mean year length and can be a day out near a year boundary.