What a Unix timestamp is
A Unix timestamp is the number of seconds that have passed since 1 January 1970 at 00:00 UTC, a moment known as the epoch. Servers and databases store time this way because a single number is easy to sort and compare.
Reading a timestamp
Ten digits usually means seconds. Thirteen digits usually means milliseconds, which is what JavaScript uses. If a converted date looks far in the future, you probably entered milliseconds.
Time zones
The timestamp itself is always UTC. The readable date depends on the time zone of the computer displaying it.
Frequently asked questions
Why does my timestamp convert to 1970?
A very small number is only a few seconds after the epoch, so it shows as January 1970.
Is the timestamp in seconds or milliseconds?
Unix timestamps are in seconds. JavaScript uses milliseconds, which is 1000 times larger.
What is the current Unix time?
The live value at the top of the page updates every second.