Unix Timestamp Converter guide
Convert Unix seconds or milliseconds into readable dates, or turn a local date and time into both timestamp formats.
What this tool does
The Unix Timestamp Converter supports two directions. Unix-to-date mode interprets a numeric value as seconds or milliseconds since the Unix epoch and reports ISO 8601 UTC plus the browser’s local date and time. Date-to-Unix mode treats the selected date and time as local to the current browser and returns whole seconds and milliseconds.
The Unix epoch begins at 1970-01-01 00:00:00 UTC. A seconds timestamp commonly contains about ten digits for modern dates, while milliseconds commonly contains thirteen. Automatic detection treats absolute values of 100 billion or more as milliseconds. Explicit unit selection is safer when working with historical, far-future, or unusual application data.
Unix time represents an instant, not a named time zone. The same instant can be displayed with different clock times in Karachi, London, or New York. ISO output uses Z to identify UTC, while local output follows the time zone configured on the current device.
How to use it
- Choose Unix-to-date or date-to-Unix mode.
- For Unix input, enter the number and select automatic, seconds, or milliseconds.
- For date input, choose a local date and clock time.
- Select the conversion button.
- Copy the format required by your database, API, log, or development tool.
Use the current-time shortcut when you need a seconds timestamp for testing. Remember that the displayed local time depends on device settings.
Benefits
- Converts in both directions
- Supports seconds and milliseconds
- Displays UTC ISO and browser-local time together
- Includes an explicit unit override
- Runs locally without sending dates to a service
Time-zone and precision notes
The datetime-local input does not contain a time-zone identifier. JavaScript interprets it in the browser’s current zone, including the applicable daylight-saving offset. Ambiguous or nonexistent local clock times around daylight-saving transitions can behave differently across environments.
Seconds output is rounded down to the complete second. Milliseconds retains the precision supplied by the browser date value. Unix timestamps do not directly encode leap seconds, calendar names, or a future time-zone rule.
For financial, legal, medical, or audit records, confirm the required time zone, precision, clock source, and formatting rules with the authoritative system.