Unix timestamp

Convert between timestamps and UTC dates

A Unix timestamp describes a moment as a number of seconds relative to 1 January 1970 at 00:00:00 UTC, called the Unix epoch. It is a common format in logs, APIs, databases, and exported data. This tool helps you inspect that number or generate a timestamp from a known UTC date and time.

1. Choose the conversion direction

   Use Timestamp → date to read a number, or Date → timestamp to create one.

2. Enter seconds or a UTC date

   The number field expects whole seconds. In the date direction, the clock time you enter is interpreted as UTC.

3. Read the result and its unit

   Select Calculate. A readable result is labelled UTC; a numeric result is a timestamp in seconds.

Reference values around the epoch

Negative timestamps are valid: they describe times before the epoch. Zero is the epoch itself, rather than an empty value. These small reference values are useful when checking an import routine because you can work out the expected answer without relying on a modern, many-digit timestamp.

Seconds versus milliseconds

This converter uses seconds. Some systems, including JavaScript date values, use milliseconds instead. There are one thousand milliseconds in one second. Passing a millisecond value into a seconds field interprets the number at a completely different scale. Check the source documentation or schema rather than guessing only from the number of digits.

When converting a millisecond value manually, divide it by one thousand. If that produces a fraction, decide whether you need to retain subsecond precision elsewhere; this tool accepts only whole-number seconds. Do not silently round an event timestamp if the fraction matters to ordering or measurement.

UTC and your local clock

A timestamp identifies an instant, while the same instant can be displayed with different local clock times. The readable output here always uses UTC. The date input also uses UTC even if your device is in another zone. If you start with a local appointment time, use the time zone converter to establish its UTC date and time first.

Checking exported data

Convert one event whose date you already know before processing a larger set. Confirm the unit, whether negative values are permitted, and whether a zero means the epoch or is being used as a missing-value convention by that system. Extremely large values outside the browser’s date range are rejected. The Unix timestamp guide explains more of the conventions, including why Unix time does not count leap seconds as separate timestamp seconds.