What is a Unix timestamp

A Unix timestamp is the number of seconds that have passed since 00:00:00 UTC on 1 January 1970, not counting leap seconds. Programmers store it because it is a single integer that any timezone can format later.

Seconds versus milliseconds

Many APIs use seconds (10 digits for current dates). JavaScript’s Date.now() uses milliseconds (13 digits). If a number looks about a thousand times too large, divide by 1000 before you treat it as seconds.

Why it looks ugly

1_704_067_200 is harder to read than “1 January 2024”. Logs still prefer the integer because it sorts correctly and does not depend on a locale. Convert it only when a human needs to read the moment.

Use the Unix Timestamp Converter to move between epoch seconds and a readable ISO date.