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Turn epoch seconds, milliseconds, microseconds or nanoseconds into a date, and a date back into a timestamp.
A Unix timestamp is the number of seconds since 00:00:00 UTC on 1 January 1970, the Unix epoch. Leap seconds are not counted: every day is treated as exactly 86,400 seconds long. It is a single number with no time zone, which is why logs, databases, JWT claims and APIs use it to name the same moment everywhere.
Many systems count in finer units. Date.now() in JavaScript and System.currentTimeMillis() in Java return milliseconds, PostgreSQL timestamps and Python datetime values resolve microseconds, and UnixNano() in Go and the OpenTelemetry protocol use nanoseconds. Each finer unit makes the number three digits longer.
With Auto, the tool counts the digits: up to 11 is read as seconds, 12 to 14 as milliseconds, 15 to 17 as microseconds and 18 or more as nanoseconds. That is right for every moment from March 1973 to the year 5138. A millisecond, microsecond or nanosecond value from before March 1973 has fewer digits and would be read as a coarser unit, so choose the unit yourself for those.
A number with a decimal point, such as 1794650400.5, is read in the same way and keeps its fraction down to the nanosecond.
You can also type a date such as 2026-11-14T10:00:00Z or 14 Nov 2026 10:00 to get its timestamp. A date that carries an offset or a Z is read as written. A date without one is read in the time zone your browser reports, which the line under the field names.
A date that does not exist, such as 2026-02-30, is reported as an error instead of being moved to the next month. So is a date written with a month name and no year, such as 14 Nov, because the year would have to be guessed.
A Unix timestamp has no time zone: it counts seconds from the epoch, which is defined in UTC. The tool shows that moment both in UTC (ISO 8601 and RFC 2822) and in the time zone your browser reports.
Systems that store the timestamp in a signed 32-bit integer can count only to 2,147,483,647, which is 03:14:07 UTC on 19 January 2038. One second later the value overflows. Systems that use 64-bit integers are not affected.
Yes. A negative number is a moment before 1 January 1970. For example, -86400 is 00:00:00 UTC on 31 December 1969.
No. The conversion is done by JavaScript in your browser tab, and the tool makes no network request with what you type.