Unix Timestamp Converter
Convert Unix time in seconds or milliseconds to local time, UTC, and ISO 8601, or convert a local date and time to Unix seconds and milliseconds. The unit is never guessed.
What Is a Unix Timestamp Converter?
A Unix timestamp (epoch time) counts whole seconds or milliseconds from 1 January 1970 00:00:00 UTC. This converter turns that integer into local time, UTC, and ISO 8601, and turns a local date and time back into Unix seconds and milliseconds. It is not the Time Converter, which only converts fixed durations.
How to Use This Converter
- Timestamp to date — Enter an integer, choose Seconds or Milliseconds yourself, then click Convert timestamp.
- Date to timestamp — Pick a local date and time, then click Convert date/time. The value is read in this browser’s timezone.
- Copy — Use Copy on a result row to copy that value only.
Seconds versus milliseconds
The same digits mean different instants if you pick the wrong unit. This tool never infers the unit from digit length. Negative integers are allowed and represent times before 1970 when they fall inside JavaScript’s Date range.
Examples
- 0 seconds → ISO 8601
1970-01-01T00:00:00.000Z(Unix epoch). - −1 second → ISO 8601
1969-12-31T23:59:59.000Z. - −1 millisecond → ISO 8601
1969-12-31T23:59:59.999Z; whole Unix seconds =Math.floor(-1 / 1000)=-1.
Frequently Asked Questions
Does this tool use my timezone?
Local results and the datetime-local field use the timezone configured on this browser or device. UTC and ISO 8601 do not. Named time zones cannot be selected.
What happens around daylight saving time?
datetime-local has no offset. If a local time is skipped or repeated when clocks change, the browser chooses which instant it means. This converter uses that instant.
Why are decimals and 1e12 rejected?
The timestamp must be a whole integer so the value is not rounded or truncated. Scientific notation and fractions are not accepted.
Is this converter free?
Yes. It runs in your browser with no registration required.