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Unix timestamp converter

Convert epoch seconds or milliseconds to a UTC date and time, and back again.

Examples & help

Unix timestamp to UTC date

Convert Unix seconds or milliseconds to a date

Choose the unit explicitly. Negative values are before 1970. Seconds can have up to three decimal places; milliseconds must be whole numbers.

Convert a UTC date and time to Unix time

UTC date to Unix timestamp

The entered time is UTC, regardless of your device’s time zone.

Enable JavaScript to convert timestamps. Nothing is saved or sent.

EXAMPLES & HELP

How to convert a Unix timestamp to a date

Unix timestamps describe an instant as a number measured from 1 January 1970 at midnight UTC. They appear in logs, APIs and exported data. The important first question is whether the number is in seconds or milliseconds.

How to use this calculator

  1. Paste the timestamp without grouping commas and choose Seconds or Milliseconds.
  2. Select Convert timestamp to see the UTC date and both numeric units.
  3. For the reverse conversion, enter a UTC date and time in the second form and select Convert UTC date.

Worked examples

The start of the Unix epoch

Start with
Timestamp: 0. Unit: Seconds.
Result
1970-01-01T00:00:00.000Z

Zero is midnight at the beginning of 1 January 1970 in UTC. A negative timestamp represents an earlier instant. Your local clock can show a different date for that same moment.

Seconds and milliseconds for New Year 2024

Start with
Timestamp: 1704067200000. Unit: Milliseconds.
Result
2024-01-01T00:00:00.000Z — also 1704067200 seconds.

Both numbers describe midnight UTC on 1 January 2024. There are 1,000 milliseconds in one second. Choosing seconds for the longer number would give a very different result or a range error.

Common questions

How do I tell seconds from milliseconds?

Check the field definition or API documentation that supplied the value. Present-day seconds often have 10 digits and milliseconds often have 13, but length is only a clue. This tool requires an explicit unit.

Is the UTC date field using my local time zone?

No. The label is UTC: entering 09:00 means 09:00 UTC regardless of your device setting. Convert your local date and time to UTC first if that is the instant you intend.

What precision and date range are supported?

The calculator supports years 0001–9999 and millisecond precision. Seconds may have up to three decimal places; milliseconds must be whole numbers. Leap-second values such as 23:59:60 are not represented.