Developer Tools

Unix Timestamp Converter

Convert signed Unix timestamps to readable dates using explicit time units, or turn a UTC or browser-local date into epoch values from seconds through nanoseconds.

Seconds to nanosecondsUTC and local inputIANA display zones

Convert Unix time and dates

Unix Timestamp Converter

Convert explicit epoch units with millisecond dates and separately preserved sub-millisecond precision.

Input and options
Explicit units; no magnitude guessing.
Signed integer; up to 30 digits.
Examples: America/New_York or Asia/Dubai. Blank uses UTC.

How this tool works and limits

Epoch arithmetic uses BigInt; date rendering uses JavaScript Date (millisecond precision, range ±8,640,000,000,000,000 ms). Sub-millisecond remainder is nonnegative after flooring to milliseconds, including negative timestamps. UTC day-of-year and weekday are reported. Input dates support years 0001–9999; local DST gaps are rejected, repeated times use the browser’s earlier occurrence. IANA zones are display-only. No leap-second modeling or live timer.

Your input is processed locally in your browser and is not uploaded or stored by this tool.

Precise local epoch arithmetic

Conversion runs in your browser. The selected IANA zone changes only the readable display; it does not rewrite the underlying timestamp.

How to use the Unix timestamp converter

  1. 1

    Choose Timestamp to Date, Date to Timestamp or Current Unix Time.

  2. 2

    For a timestamp, select seconds, milliseconds, microseconds or nanoseconds and enter a signed integer.

  3. 3

    For a date, enter the calendar date, time, milliseconds and UTC or Browser Local interpretation.

  4. 4

    Add an optional IANA display zone such as America/New_York or Asia/Dubai.

  5. 5

    Review every epoch unit, ISO UTC output, local display and sub-millisecond remainder.

What is a Unix timestamp?

A Unix timestamp measures elapsed time from the Unix epoch at 1970-01-01 00:00:00 UTC. Standard timestamps are often expressed as whole seconds, while browser and database systems may use milliseconds, microseconds or nanoseconds. Negative values represent instants before the epoch.

Unix timestamp example

The value 1704067200 seconds converts to 2024-01-01T00:00:00.000Z. The same instant is 1704067200000 milliseconds. Entering 1704067200123456789 nanoseconds preserves the fractional epoch value, while the ISO date display is floored to millisecond precision and separately reports the remaining nanoseconds.

Seconds, milliseconds, microseconds and nanoseconds

This converter never guesses a unit from the number of digits. Choose it explicitly so a ten-digit seconds value is not mistaken for milliseconds. Epoch arithmetic uses exact integer handling. Readable date rendering relies on the browser’s JavaScript Date range and millisecond resolution, so finer precision is shown separately.

UTC, browser-local time and display zones

Timestamp values themselves are absolute instants. UTC is the safest date-input interpretation for data exchange. Browser Local uses the time zone configured on the current device; a daylight-saving gap is rejected, while a repeated local time uses the browser’s earlier occurrence. An IANA zone affects only the formatted display.

Important technical limitations

  • Date range: output must fit the JavaScript Date range of approximately ±8.64 quadrillion milliseconds.
  • Leap seconds: Unix/JavaScript time here does not model leap seconds.
  • No live timer: Current Unix Time captures one instant when processed.
  • Local ambiguity: daylight-saving rules depend on the browser’s time-zone data.
  • Input format: timestamp input must be a signed integer of up to 30 digits.

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Unix Timestamp Converter FAQ

What is Unix time zero?

Unix time zero is 1970-01-01 00:00:00 UTC.

How do I know whether a timestamp uses seconds or milliseconds?

Check the source specification and choose the unit explicitly; this tool does not guess from length.

Can the converter handle nanoseconds?

Yes. Integer epoch arithmetic preserves nanoseconds, while readable Date output is millisecond-based.

Does changing the display zone change the timestamp?

No. It only changes how the same instant is formatted for reading.

Can I convert dates before 1970?

Yes, when the date is within the supported JavaScript Date range; the timestamp will be negative.

Are leap seconds included?

No. The converter follows standard JavaScript and Unix-style epoch behavior without leap-second modeling.

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