Unix Timestamp Converter
Convert Unix (epoch) timestamps to readable dates, and dates back to timestamps, in UTC and your own time zone.
Seconds since 1970-01-01 00:00:00 UTC (POSIX) ยท By Stuart Mathieson · Updated October 2026
Current Unix time
seconds milliseconds
Timestamp to date
Local time is .
Date to timestamp
Everything runs in your browser - nothing you enter is sent to a server.
What is Unix time?
Unix time (also called epoch time or POSIX time) counts the seconds since 00:00:00 UTC on 1 January 1970, the "Unix epoch". It is the same number everywhere in the world at a given moment, which is why computers use it to store and compare times. Time zones only come in when the number is shown as a date.
| Timestamp | Date (UTC) |
|---|---|
| 0 | 1970-01-01 00:00:00 |
| 1,000,000,000 | 2001-09-09 01:46:40 |
| 1,700,000,000 | 2023-11-14 22:13:20 |
| 2,147,483,647 | 2038-01-19 03:14:07 |
| -86,400 | 1969-12-31 00:00:00 |
Negative timestamps are dates before 1970. Every day counts as exactly 86,400 seconds: POSIX time ignores leap seconds, so it isn't quite a count of elapsed seconds, but it makes date arithmetic simple.
Seconds or milliseconds?
Unix systems, most databases and many APIs use seconds - currently 10 digits. JavaScript, Java and many web APIs use milliseconds - 13 digits. Some systems use microseconds (16 digits) or nanoseconds (19 digits). Detect picks the unit from the size of the number: anything below 100 billion is read as seconds, which covers every date up to the year 5138. A millisecond timestamp from before March 1973 would be misread, so choose the unit yourself for those.
The year 2038 problem
Older systems store Unix time in a signed 32-bit integer, which can't go above 2,147,483,647. That moment is 03:14:07 UTC on 19 January 2038. One second later, the count wraps around to -2,147,483,648, which those systems read as 13 December 1901.
Most modern operating systems and languages now use 64-bit time, which lasts for billions of years, but 32-bit time can still lurk in embedded devices, old file formats and database columns. If you work with long-dated values - 30-year mortgages, pensions, certificates - it's worth checking.
Tips
- Store and send times as UTC timestamps or ISO 8601 strings with an offset (like
2023-11-14T22:13:20Z), and convert to local time only for display. - Local times in the "date to timestamp" converter follow your device's time zone, including daylight saving time. A time skipped by a spring-forward change is moved forward; a time that happens twice in autumn uses the first occurrence.
- To compare times between cities, use the Time Zone Converter; to count days between dates, use the Date Calculator.
Frequently asked questions
What is a Unix timestamp?
The number of seconds since 00:00:00 UTC on 1 January 1970, ignoring leap seconds. For example, 1700000000 is 22:13:20 UTC on 14 November 2023.
How do I tell if a timestamp is in seconds or milliseconds?
Count the digits. Current timestamps are 10 digits in seconds and 13 digits in milliseconds. JavaScript's Date.now() returns milliseconds; Unix tools usually use seconds.
What happens in 2038?
A signed 32-bit counter of seconds runs out at 03:14:07 UTC on 19 January 2038 and wraps to a negative number, read as 1901. Systems using 64-bit time are not affected.
Does Unix time depend on my time zone?
No. A Unix timestamp is the same everywhere at a given moment. Only the readable date and time it is shown as depends on the time zone.
Sources
- Base Definitions, section 4.16: Seconds Since the Epoch - The Open Group, POSIX.1-2017
- Date - MDN Web Docs