Unix Timestamp Converter

About Unix Timestamp Converter

Unix Timestamp Converter translates numeric timestamps into readable dates and converts a local date and time back into Unix time. It supports seconds and milliseconds, with output shown as local time, UTC and ISO 8601. Use it when inspecting event logs, API fields or expiration times that are stored as numbers rather than familiar dates.

Choosing the correct unit matters: treating seconds as milliseconds can place a modern event near the start of the Unix epoch. Local output depends on your browser’s time zone, while UTC describes the same instant without that local offset. Select the conversion direction and unit first, then compare the representations. Use current time fills a fresh value when you need an example of the current instant.

How it works

JavaScript Date represents instants in milliseconds relative to 1 January 1970 at 00:00:00 UTC. In Timestamp → Date mode, the tool multiplies a seconds input by 1,000 or uses a milliseconds input directly, then creates a Date. In Date → Timestamp mode, it interprets the date-time field as a local browser date and obtains the corresponding millisecond value. Seconds output is the millisecond value divided by 1,000 and rounded down.

The output rows are different representations of that same instant. Local date/time uses the browser’s locale and time zone; UTC date/time and the ISO string use UTC, with Z marking UTC in ISO output. A time zone affects how an instant looks, not the underlying timestamp. The date-time input has no separate time-zone selector and ordinarily records minute-level input, so use caution when reconstructing a source value that includes seconds, milliseconds or an ambiguous daylight-saving time.

When is this useful?

• Read a timestamp from an API or log.
• Compare a local event time with UTC output.
• Create a numeric timestamp from a local development date.

Things to know

• The local date-time field uses the browser’s time zone, without a time-zone selector.
• Seconds output is rounded down; date-time input does not expose sub-minute precision.
• Values outside the browser’s supported Date range are rejected.

Privacy & processing

The converter uses JavaScript Date functions in this browser. It does not send timestamps to a date-conversion service; Use current time reads the device clock.