Unix Timestamp accuracy and testing

Formula source

• The Unix Timestamp is a simple count of seconds. * **To Timestamp:** Calculate the difference in milliseconds between the input date and Jan 1, 1970 00:00:00 UTC, then divide by 1000. * **To Date:** Multiply the timestamp by 1000 to get milliseconds, then create a new Date object.

Test cases

Known limitations

• This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
• Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

• Standard Unix timestamps are treated as seconds since January 1, 1970 00:00:00 UTC.
• Date input uses the browser's local timezone before conversion to the UTC-based epoch value.
• This tool expects 10-digit second timestamps rather than 13-digit millisecond values unless you convert them first.

Unit handling

• Conversion Mode accepts one of the configured options.
• Date (for mode 1) accepts calendar dates.
• Time (for mode 1) accepts local time values.
• Timestamp (for mode 2) accepts numeric values.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.

Version history

Change log