Unix Time Converter
Convert a Unix timestamp to a readable date, or a date to a timestamp — seconds or milliseconds.
Every common format
| Format | Value |
|---|---|
| ISO 8601 (UTC) | 2026-07-14T03:33:20Z |
| RFC 2822 | Tue, 14 Jul 2026 03:33:20 +0000 |
| UTC | Tue, 14 Jul 2026 03:33:20 UTC |
| Seconds | 1784000000 |
| Milliseconds | 1784000000000 |
| Day of year | 194 (week 29) |
What a Unix timestamp is
It is a count of seconds since 1 January 1970, 00:00:00 UTC — the Unix epoch. Because it is a single integer in a single time zone, it is unambiguous, sorts correctly and does arithmetic easily, which is why almost every database, log file and API uses it internally.
Negative values are dates before 1970, which is legal and works fine.
Seconds or milliseconds?
Unix time is defined in seconds, but JavaScript's Date.now()
returns milliseconds, so the two get mixed up constantly. The tell is the
length: a present-day timestamp in seconds is 10 digits, and in milliseconds it
is 13. This calculator detects which you pasted.
Leap seconds and the 2038 problem
Unix time deliberately ignores leap seconds — every day is treated as exactly 86,400 seconds — so it is not a true count of elapsed SI seconds. Separately, systems that store the timestamp in a signed 32-bit integer overflow on 19 January 2038. Modern platforms use 64-bit, which pushes the limit far beyond the lifetime of the sun.