What Is a Unix Timestamp?
A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC. For example, the timestamp 1700000000 represents November 14, 2023 at 22:13:20 UTC.
Why Was January 1, 1970 Chosen?
The Unix epoch was chosen by the original Unix developers in the late 1960s as a convenient, recently-past reference point. There was no deeper significance — it was simply round and recent enough to be practical for the systems of that era.
Seconds vs Milliseconds
Most Unix timestamps are expressed in seconds (10 digits, e.g. 1700000000). JavaScript and many modern APIs use milliseconds (13 digits, e.g. 1700000000000). Always check which unit an API expects — passing seconds where milliseconds are expected will result in dates in January 1970.
How to Use Timestamps in Code
In PHP: time() returns the current Unix timestamp in seconds. In JavaScript: Date.now() returns milliseconds, Math.floor(Date.now()/1000) gives seconds. In Python: import time; time.time().
Convert Timestamps Instantly
Our Unix Timestamp Converter converts timestamps to UTC, ISO 8601, local time and relative time formats. It also converts any date back to a Unix timestamp with a simple date picker.
