Unix Timestamp Converter

What this tool does

Paste a Unix timestamp and the tool shows the same moment in four forms: UTC, your local time, ISO 8601, and a relative description such as “3 hours ago”. Leave the box empty and it uses the current time. You can also enter a calendar date and get the epoch seconds back.

Seconds or milliseconds

A Unix timestamp counts seconds since 1 January 1970 UTC. JavaScript and many APIs use milliseconds instead. The tool guesses which one you pasted from the length: a value of 10 digits or fewer is treated as seconds, and anything longer is treated as milliseconds.

That rule is right for dates between 2001 and 2286, which covers almost everything you will meet. It gets it wrong for very early dates (for example a second-based value with fewer digits), and for negative timestamps. If the result looks like 1970, try adding three zeros, or removing them.

Time zones

The UTC and ISO lines are unambiguous. The “local” line uses the time zone of your browser, so it will differ from someone in another country looking at the same page. When you are debugging a log or a cron job, compare in UTC to avoid confusion.

Typical uses

• Reading exp and iat values from a token. The JWT decoder shows those already, but this is useful for other fields.
• Converting a database created_at stored as an integer
• Working out when a WordPress transient or cookie expires
• Checking that two systems are using seconds, not milliseconds

Limits

It works on timestamps JavaScript’s Date can represent, roughly the years 271821 BC to 275760 AD. Leap seconds aren’t represented, which matches how Unix time works.