Timestamp FAQ
Answers about Unix timestamps, timezone interpretation, and local-first conversion.
What is a Unix timestamp?
A Unix timestamp is the number of seconds or milliseconds before or after 1970-01-01T00:00:00Z.
What is the difference between seconds and milliseconds?
Seconds are commonly used by APIs and may include up to three decimal places. Milliseconds are whole numbers and preserve the same precision.
What do Local and UTC mean?
UTC interprets the entered date and time at +00:00. Local uses your browser’s current system timezone; the result shows its timezone name and offset.
How are daylight-saving changes handled?
Times skipped by a daylight-saving change are rejected. For a repeated local time, the browser chooses the earlier offset and Timestamp shows the resulting offset.
What precision and range are supported?
Timestamp preserves integer milliseconds within the JavaScript Date range. Seconds accept no more than three fractional digits; values outside that range are rejected.
Do my values leave this device?
No. Timestamp converts in the current page only. It does not send, store, log, or put entered values into URLs.
Why are natural-language dates not accepted?
Natural-language parsing is intentionally not part of this precise MVP. Planned work may add it alongside arbitrary IANA timezones, relative times, share links, and a manual theme switcher; no release date is promised.
See the converter or read the JavaScript Date documentation.