Free Unix Timestamp Converter
Convert Unix epoch timestamps to human-readable dates and back. Seconds and milliseconds are detected automatically.
Timestamp → Date
| Detected unit | |
|---|---|
| UTC | |
| Your timezone | |
| ISO 8601 | |
| Relative |
Date → Timestamp
| Unix seconds | |
|---|---|
| Unix milliseconds |
Why computers count time as a single number
A Unix timestamp sidesteps timezones and calendars entirely by counting elapsed seconds from one fixed reference point: midnight UTC on January 1, 1970 — the "Unix epoch," picked as a convenient recent reference point when Unix time-keeping was standardized in the early 1970s. Storing time this way means a database, log file, or API never has to store or interpret a timezone alongside the value — two servers on opposite sides of the world agree on exactly what moment timestamp 1782000000 refers to, and any display timezone or formatting is applied only when a human needs to read it.
The 2038 problem, precisely
Older systems that store a Unix timestamp in a signed 32-bit integer can only count up to 2,147,483,647 seconds past the epoch — which lands on January 19, 2038, at 03:14:07 UTC. One second later, the counter overflows and wraps to a negative number, which historically-32-bit systems can misread as December 1901. Modern systems store timestamps as 64-bit integers instead, which pushes the same overflow point trillions of years into the future — effectively a non-issue for 64-bit software, but still a real constraint on old embedded and legacy systems.
Frequently Asked Questions
What is a Unix timestamp?
A Unix timestamp (or epoch time) is the number of seconds elapsed since January 1, 1970, 00:00:00 UTC. It is the standard way computers store points in time because it is timezone-independent and easy to compare.
How do I know if my timestamp is in seconds or milliseconds?
Current timestamps in seconds are 10 digits; in milliseconds they are 13 digits. This tool auto-detects the unit: values of one trillion or more are treated as milliseconds.
What happens in 2038?
Systems that store timestamps as signed 32-bit integers overflow on January 19, 2038. Modern systems use 64-bit integers, which push the limit billions of years out. JavaScript (and this tool) handles dates far past 2038.
Why was January 1, 1970 chosen as the starting point?
It wasn't tied to any historical event — early Unix developers simply needed a fixed, reasonably recent reference point when they standardized how the system tracked time in the early 1970s, and January 1, 1970 was chosen as a clean, convenient date.
What's the difference between epoch time and ISO 8601?
Epoch time is a single integer with no embedded timezone — you must know separately what timezone to display it in. ISO 8601 (like 2026-07-17T14:30:00Z) is a human-readable string format that encodes the timezone or UTC offset directly, so it's unambiguous on its own.
Does the converter account for daylight saving time?
Yes. Conversions to and from "My timezone" use your browser's timezone database, which includes daylight saving rules for your region.