Timestamp & date converter
Convert between Unix seconds, Unix milliseconds, and ISO 8601, auto-detected from the input shape. Runs on your device.
Runs on your device. The file is never uploaded.
Timestamp & date converter reads an ISO 8601 string, Unix seconds or Unix milliseconds and prints five lines back. Those are the ISO form, both Unix forms, the UTC string and the weekday, all of them in UTC. A digits-only input below 1e11 is taken as seconds and anything larger as milliseconds, a guess the number itself cannot settle.
Questions
What can I paste into it?
Unix seconds, Unix milliseconds, or an ISO 8601 date string. The shape of the input decides: all digits with an optional minus sign is treated as a number, anything else goes to the browser date parser. The field starts filled with the current time in seconds.
How does it tell seconds from milliseconds?
By magnitude. An absolute value below 1e11 is read as seconds and multiplied by 1000; anything larger is read as milliseconds. The number itself carries no unit, so this is a heuristic, and it is the same one every epoch tool uses. It only breaks past the point where 1e11 seconds falls, in the year 5138.
Which time zone are the results in?
UTC, all of them. The ISO line is the standard ISO string, the UTC string line is the RFC-style UTC form, and the day of the week is computed with the time zone pinned to UTC. There is no local-time output and no time zone option, so the page reads the same wherever you are.
What does it print?
Five lines: the ISO 8601 form, Unix seconds floored to a whole number, Unix milliseconds, the UTC string form, and the day of the week spelled out in English. Milliseconds survive in the ISO line even where the seconds line has dropped them.
Why did my date fail to parse?
Because the browser date parser rejected it, and the message quotes your input and says it failed to parse as a Unix timestamp or ISO 8601 date. Formats such as 25/12/2024 are ambiguous and unreliable across browsers; write 2024-12-25 or 2024-12-25T13:45:00Z instead. A stray space inside a digits-only value also pushes it down the date path.
Does the page send my timestamps anywhere?
No. It reads the field, does the arithmetic with the browser date object inside a Web Worker, and prints the result. Nothing is uploaded, nothing is kept between runs, and the page still converts with the network switched off after the first visit.