The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970 (midnight UTC/GMT), not counting leap seconds (in ISO 8601: 1970-01-01T00:00:00Z).

Is Unix timestamp in seconds or milliseconds?

Epoch, also known as Unix timestamps, is the number of seconds (not milliseconds!) that have elapsed since January 1, 1970 at 00:00:00 GMT (1970-01-01 00:00:00 GMT).

How long is a Unix timestamp?

As I write this, a current UNIX timestamp would be something close to 1292051460 , which is a 10-digit number. Assuming a maximum length of 10 characters gives you a range of timestamps from -99999999 to 9999999999 .