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Unix Timestamp Converter

Convert Unix timestamps (in seconds or milliseconds) to human-readable dates, and convert dates back to Unix epoch time.

What is a Unix timestamp?

A Unix timestamp is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, the Unix epoch. It's a time-zone-independent way to represent an instant in time and is used widely in programming, databases, and APIs. JavaScript and many web APIs use milliseconds instead of seconds.

Seconds vs milliseconds

UnitExample (now)Used by
Seconds10 digits, e.g. 1700000000Unix, MySQL, Python, Go, most REST APIs
Milliseconds13 digits, e.g. 1700000000000JavaScript (Date.now), Java, many JSON APIs

Timestamp → Date

Date result

Local time (UTC)
1/1/1970, 12:00:00 AM
UTC (Coordinated Universal Time)
Thu, 01 Jan 1970 00:00:00 GMT
ISO 8601 (UTC)
1970-01-01T00:00:00.000Z
Unix (s / ms)
0 / 0

Local time is shown in your browser's time zone; UTC and ISO 8601 are time-zone independent and identical for everyone.

Date → Timestamp

Uses your browser's local time zone.

Timestamp result

Unix seconds
1785817260
Unix milliseconds
1785817260000
Local
8/4/2026, 4:21:00 AM
UTC
Tue, 04 Aug 2026 04:21:00 GMT

How to convert a Unix timestamp to a date

  1. Paste the timestamp into the Unix timestamp field.
  2. Pick Seconds (10-digit) or Milliseconds (13-digit).
  3. Read the local time, UTC, and ISO 8601 formats from the result.
  4. To go the other way, enter a date and time in the second card to get its timestamp in both units.

Example

1700000000 seconds is 2023-11-14 22:13:20 UTC.

Learn more

Background: Unix time (Wikipedia) · Coordinated Universal Time (UTC).

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Frequently asked questions

What is a Unix timestamp?
The number of seconds (or milliseconds) since 1970-01-01 00:00:00 UTC, the Unix epoch. It's a time-zone-independent way to represent an instant.
Seconds or milliseconds?
Seconds is the classic Unix timestamp. JavaScript and many APIs use milliseconds — Calcadian supports both.
Does the converter handle time zones?
Yes — the second section uses your browser's local time zone for input, and the output shows both local and UTC times.
What's the largest timestamp it accepts?
JavaScript supports dates up to roughly the year 275760, well past any practical use.
Is anything sent to a server?
No. Conversions run entirely in your browser.

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