Unix time counts seconds elapsed since 00:00:00 UTC on 1 January 1970. It is the standard way computers store a moment in time, because it is a single integer with no timezone, no locale and no formatting ambiguity.
How to use the Unix Timestamp Converter
- Paste a timestamp to convert it to a readable date
- Or pick a date to get its timestamp
- Check whether your source uses seconds (10 digits) or milliseconds (13)
- Note that timestamps are UTC — convert to local time separately if needed
Seconds or milliseconds
The most frequent source of confusion. Unix time is defined in seconds, but JavaScript's Date.now() returns milliseconds, and many APIs follow suit.
Tell them apart by length: a seconds timestamp for the current era has 10 digits, milliseconds has 13. If a date comes out in 1970, you passed milliseconds to something expecting seconds. If it lands tens of thousands of years in the future, you did the reverse.
The 2038 problem
Systems storing Unix time in a signed 32-bit integer overflow at 03:14:07 UTC on 19 January 2038, wrapping to December 1901. It is the same class of bug as Y2K, and it is not hypothetical — embedded systems, older databases and some file formats are still affected.
Modern platforms use 64-bit timestamps, which push the limit roughly 292 billion years out. Anything long-lived or embedded is worth checking now rather than in 2037.
One more subtlety: Unix time ignores leap seconds, so it is not a true count of elapsed SI seconds. That is deliberate — it keeps the arithmetic simple at the cost of being very slightly out of step with astronomical time. Almost nothing cares, but precise scientific timing does.
Frequently asked questions
Why does my timestamp convert to 1970?
You passed a value in seconds to something expecting milliseconds, or the value is near zero. A current-era seconds timestamp has 10 digits; milliseconds has 13.
Are Unix timestamps timezone-aware?
No, and that is the point. A timestamp is an absolute moment in UTC. Timezone is a display concern applied when formatting it for a person.
What happens in 2038?
Signed 32-bit timestamps overflow on 19 January 2038 and wrap to 1901. Modern 64-bit systems are unaffected, but legacy embedded devices and older data formats may not be.
Does Unix time account for leap seconds?
No. It assumes every day is exactly 86,400 seconds, so it drifts slightly from atomic time. This keeps date arithmetic simple and is irrelevant for almost all applications.