Convert Unix timestamps to human dates and back. Seconds and milliseconds supported, UTC and local time shown.
| Input | Output |
|---|---|
| 1735689600 | 2025-01-01 00:00:00 UTC |
| 1735689600000 (13 digits) | same instant, milliseconds input |
| 2025-06-15 12:00 | 1749988800 (in your local zone) |
The number of seconds elapsed since 1970-01-01 00:00:00 UTC (the Unix epoch). It is timezone-independent, which is why APIs, databases and logs use it everywhere.
Count the digits: 10 digits is seconds (until the year 2286), 13 digits is milliseconds. JavaScript's Date.now() returns milliseconds; most server logs and APIs use seconds.
The instant is the same everywhere — only the display differs. UTC is the universal reference; the Local line shows the same instant in your device's timezone.
Systems storing the timestamp as a signed 32-bit integer overflow on 2038-01-19. This converter uses 64-bit numbers, so dates far beyond 2038 convert correctly.