Unix Timestamp Converter

What is a Unix timestamp?

A Unix timestamp is the number of seconds that have elapsed since 1 January 1970 00:00:00 UTC, a moment known as the Unix epoch. Because it is a single integer, it is the standard way to store and compare instants in logs, APIs, databases and file systems. The same instant is written as 1700000000 whether you are in Madrid, New York or Tokyo.

Seconds or milliseconds?

Most languages use seconds, but JavaScript’s Date.now() returns milliseconds. The two differ by a factor of 1,000, so the same moment can be 1700000000 (seconds) or 1700000000000 (milliseconds). This tool detects both and tells you which unit it used.

Converting timestamps

To read a timestamp, convert it to a date in your own time zone. The epoch itself is always expressed in UTC, so the same timestamp maps to a different wall-clock time depending on where you are. 1700000000 is 22:13:20 UTC on 14 November 2023, but 23:13:20 in Central European Time. To create a timestamp, take a date and compute the seconds since the epoch.

When to use each direction

• Use a timestamp when storing, sorting or comparing events in code, logs and databases.
• Use a human-readable date when displaying a value to users or debugging one specific event.

Common mistakes

• Confusing seconds and milliseconds, which shifts every date by a factor of 1,000.
• Reading a UTC timestamp in your local time zone and misinterpreting the hour.
• Storing a date as a formatted string instead of a timestamp, which breaks sorting and comparisons.