Unix timestamp converter
Convert between Unix time and a UTC date, both directions.
Fill in the fields and the result will appear here automatically.
Counts seconds from the first of January 1970 and back again, always in UTC. The browser timezone deliberately does not enter: the same number has to give the same date for everyone, otherwise a shared link would show something different to each reader. Negative values are ordinary dates before the epoch.
How it works
Formula and logic
Integer Unix seconds are counted from 1970-01-01T00:00:00Z. The model uses the UTC Gregorian calendar, years 0001–9999 and 86,400-second days; leap seconds are not modelled. Calendar validity is checked: 1900-02-29 is rejected and 2000-02-29 is valid. Hours 0–23 and minutes/seconds 0–59 must be integers. Timestamp range is −62,135,596,800…253,402,300,799. Millisecond input is not accepted.
Example
1 700 000 000 corresponds to 2023-11-14 22:13:20 UTC, a Tuesday.
Fields and units
- Direction — list option
- Unix time — s
- Date (UTC) — date
- Hour — h
- Minute — min
- Second — s
How to use
- — Choose which direction you need.
- — Enter the timestamp, or the date and time in UTC.
- — Read the converted value and the day of the week.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- ECMAScript: Gregorian UTC, epoch and years 0–99 (draft)
- Limitation
- Deterministic conversion of whole seconds and valid UTC dates, years 0001–9999. No timezone conversion, current-time lookup, leap seconds or millisecond fraction.
FAQ
Why UTC only?
So the same timestamp always shows the same date. Applying the reader timezone would make a shared result mean different things on different machines.
Are leap seconds handled?
No, and neither is Unix time itself: every day is treated as exactly 86 400 seconds, which is what the standard specifies.
Can a timestamp be negative?
Yes. Negative values are dates before 1970, and they convert exactly the same way.
Seconds or milliseconds?
The input is in seconds, the usual Unix convention. Systems that count in milliseconds need the value multiplied by a thousand.