Timestamp Converter
Convert a Unix timestamp (seconds or milliseconds) to a formatted date in UTC, your local timezone or a chosen timezone, and back.
About this tool
Paste a Unix timestamp or a date and get both directions at once: epoch seconds and milliseconds, the ISO 8601 string, a full readable date in UTC and in a timezone you pick, the weekday, and how long ago (or ahead) the moment is. A bare number is treated as an epoch value and its unit is autodetected by magnitude — under 1e11 is seconds, then milliseconds, microseconds and nanoseconds — so a 10-digit and a 13-digit number for the same instant resolve identically. Anything that is not a bare number is handed to the browser's date parser (ISO 8601, RFC 2822, and the other formats it accepts); the literal word "now" uses your clock. Everything runs in your browser.
When to use it
Questions
How does it know if my number is seconds or milliseconds?
By magnitude. A value under 100 billion (1e11) is read as seconds, under 1e14 as milliseconds, under 1e17 as microseconds, and larger as nanoseconds. Timestamps for any date between roughly 1973 and the year 5138 have 10 digits in seconds and 13 in milliseconds, so the split is unambiguous in practice.
Why does the "relative" time keep changing?
It is measured against the moment you are looking at the page, not a fixed reference, and it is recomputed on every render. "2 minutes ago" becomes "3 minutes ago" as real time passes.
Are daylight-saving and historical timezone changes handled?
Yes, as well as your browser does. The UTC and per-timezone strings are formatted with the built-in Intl date APIs, which carry the IANA timezone database — including DST rules and historical offset changes — so a summer date and a winter date in the same zone show the correct different offsets.
What counts as an invalid input?
An empty field, text that is not a recognisable date ("banana"), or a number so large the resulting date falls outside the range JavaScript can represent. Each of these shows an error instead of a guess.