Unix Timestamp to Date
Convert a Unix timestamp in seconds or milliseconds to a date. See UTC, ISO 8601 and your device’s local time, including dates before the Unix epoch.
Your timestamp result will appear here.
How to use this calculator
- Paste a Unix timestamp and select Seconds, Milliseconds or Auto detect.
- Select Convert to see ISO 8601, UTC and your device’s local time. Use the copy buttons to reuse the result in logs, API requests or debugging notes.
How it works
Unix time counts from January 1, 1970 at 00:00:00 UTC. Seconds and milliseconds describe the same instant at different scales: 1 second is 1,000 milliseconds. The ISO result ends in Z for UTC, while Readable time uses your device’s time zone.
Example
Convert 0 seconds, then try -1 second.
0 is 1970-01-01T00:00:00.000Z. -1 is 1969-12-31T23:59:59.000Z, one second before the epoch.
Common questions
How does automatic unit detection work?
An absolute value of 10,000,000,000 or more is treated as milliseconds; smaller values are treated as seconds. This is a heuristic. Select the unit explicitly for early millisecond timestamps or far-future second timestamps.
Why do UTC and local time show different dates?
They represent the same instant. A time-zone offset can move the local clock onto the previous or next calendar date; the Unix timestamp itself has not changed.
Are negative timestamps supported?
Yes. Negative values represent instants before January 1, 1970. Select the correct unit, especially for historical dates.