Unix timestamp converter
Runs entirely in your browser. Your files and data never leave your device.
| Seconds | ||
|---|---|---|
| Milliseconds |
| Detected unit | ||
|---|---|---|
| UTC (ISO 8601) | ||
| Local time | ||
| Relative time |
| Seconds | ||
|---|---|---|
| Milliseconds | ||
| UTC (ISO 8601) | ||
| UTC time | ||
| Relative time |
About this tool
A Unix timestamp counts seconds (or milliseconds, microseconds, nanoseconds) since January 1, 1970 UTC. This tool turns a timestamp into a UTC ISO 8601 string, your local time, and a relative phrase like “3 hours ago.” It also works backward: type or pick a date and get the timestamp in seconds and milliseconds.
How does it know which unit I’m using?
Timestamps come in different resolutions depending on where they came from, and this tool guesses the right one from the number of digits: 10 digits or fewer is seconds, 11 to 13 is milliseconds, 14 to 16 is microseconds, and 17 or more is nanoseconds. That covers the two you’ll run into most often without any setup: a 13-digit value from a JavaScript Date.now() call and a 10-digit one from a server log or a Unix date +%s command both convert correctly on their own. Converting the other direction, you type or pick a date and time, and the tool reads it with the same parser JavaScript’s Date constructor uses, so ISO 8601 strings and values from a datetime-local form field both work.
There’s also a live current-time readout that updates as you watch it, handy for grabbing “right now” as a timestamp without doing the math yourself. Dates far enough in the past or future to fall outside what Date can represent (roughly ±273,790 years from 1970) are rejected with an error instead of silently producing a wrong result.
Is my data sent anywhere?
No. The conversion happens entirely in your browser using the built-in Date and Intl APIs; nothing you type is sent to a server. That matters if you’re debugging a timestamp pulled from a session token, an internal log line, or anything else you’d rather not paste into a random website.
What is this actually useful for?
Typical cases: decoding a timestamp from an API response, checking when a JWT expires, converting a meeting time into your local time zone, or filling in a datetime-local field on a form. See MDN’s guide to Date and time formats and RFC 3339 for the ISO 8601 profile used on the web, or the Wikipedia entry on Unix time for how the epoch and leap seconds are handled.