Unix Timestamp Converter
Convert Unix timestamps to dates and back. Supports seconds and milliseconds.
About Unix Timestamp Converter
Unix Timestamp Converter switches between Unix timestamps (seconds since 1970-01-01 UTC) and human-readable date/time strings. Unix time is the format almost every API, log file, and database speaks because it is unambiguous — a single integer, no time zone, no locale, no calendar quirks. The converter handles both seconds and milliseconds (the JavaScript convention is milliseconds) and shows the decoded result in both your local time zone and UTC.
Worked example: the timestamp 1700000000 (in seconds) decodes to 2023-11-14T22:13:20 UTC, or 2023-11-15T09:13:20 in Sydney (which observes AEDT, UTC+11, in November). The same instant in milliseconds — 1700000000000 — decodes to the same date/time; the converter detects which form you have by magnitude and adjusts accordingly (over a trillion is treated as milliseconds; below is treated as seconds). Going the other way, pick a date and time and the converter shows the timestamp in both forms.
Two notes worth knowing. Unix time counts seconds (or milliseconds) — it is a single ever-increasing integer, which is exactly why APIs prefer it: no time-zone debate, no daylight-saving discontinuities, no calendar reform edge cases. Negative timestamps represent dates before the 1970 epoch (−631152000 is 1950-01-01 UTC). The classic '2038 problem' is when a 32-bit signed Unix timestamp overflows on January 19, 2038, 03:14:07 UTC; modern systems use 64-bit timestamps and have no overflow concern within any human-relevant span. Unix time also ignores leap seconds (the rare extra seconds inserted to keep UTC aligned with Earth's rotation), which is a non-issue for almost every application.
Conversion runs in your browser; nothing is uploaded.