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Time Utilities

Unix Timestamp Converter

Unix time counts seconds or milliseconds from 1970-01-01T00:00:00Z. This page converts that number to a local date, UTC, and ISO, and converts a date back.

Epoch to Date

Unix seconds
1710000000
Unix milliseconds
1710000000000
Local date
Saturday, March 9, 2024 at 4:00:00 PM UTC
ISO 8601
2024-03-09T16:00:00.000Z
UTC string
Sat, 09 Mar 2024 16:00:00 GMT

Date to Epoch

The input is interpreted in the browser's local time zone, which is useful when matching log timestamps or schedule events.

Unix seconds
1709985600
Unix milliseconds
1709985600000
ISO 8601
2024-03-09T12:00:00.000Z

Frequently Asked Questions

Ten digits usually means seconds, while thirteen digits usually means milliseconds. The source API or logging system is the best place to confirm the expected unit.

They represent the same instant, but UTC shows the time without a local offset. The browser local view applies the time zone configured on the device.

Yes. Use the date-to-epoch field to convert an ISO-style or datetime-local value back into Unix time.

Yes. Unix time counts from 1970-01-01T00:00:00Z. What changes is the unit, the display format, and the time zone used to render it.

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Publisher notes · reviewed 10 September 2026

Unix time is seconds, unless it is milliseconds

Unix time counts seconds since 1970-01-01T00:00:00Z, excluding leap seconds in the POSIX definition. JavaScript `Date.now()` is milliseconds. Mixing them shifts dates by a factor of 1000.

How to tell which unit you have

A 10-digit integer near 1.7e9 is seconds in the 2020s. A 13-digit integer near 1.7e12 is milliseconds. If a converted date lands in 1970 or 56000 AD, you picked the wrong unit. The tool should expose both; if you pasted a float, check whether the API used seconds with a fractional part.

Local timezone display uses the browser zone. Two reviewers in IST and UTC will see different clock times for the same instant. Store UTC in APIs; display local only at the edge.

Worked examples

  • 1 January 2025 00:00 UTC

    Unix seconds 1735689600. Milliseconds 1735689600000. If you feed the seconds value into `new Date(n)` in JavaScript you get a 1970 date because Date expects ms.

Limits of this page

  • Leap seconds are not modelled.
  • Historical timezone rule changes depend on the browser ICU data.

Sources