UnixTime

What is a Unix timestamp?

A Unix timestamp is a single number that represents a specific point in time, counted as seconds (or milliseconds) since January 1, 1970. Programs use it internally instead of a human date because it's simple to store, compare and do math with — but it's not readable on its own, which is why you often need to convert it to and from a calendar date. UnixTime does that conversion in both directions.

How to use UnixTime

1. To convert a timestamp to a date, type or paste it into the "Timestamp" field in the Timestamp → Date panel (toggle Seconds/Milliseconds first if needed, or click Now for the current time).
2. Pick a timezone from the dropdown to see the equivalent local date, UTC, ISO 8601 and relative time.
3. Click Copy ISO to grab the ISO 8601 result.
4. To go the other way, use the Date → Timestamp panel: pick a date/time and its timezone, then read off the timestamp in seconds or milliseconds.
5. Use Copy seconds or Copy ms to copy that value.

How Unix timestamps work

A Unix timestamp counts the seconds elapsed since January 1, 1970 at 00:00:00 UTC — the so-called "Unix epoch." It's independent of any timezone: it represents an absolute instant, and only when displaying it as a date do you choose which zone to interpret it in:

1755500000 (seconds)
→ UTC:               2025-08-18 06:53:20
→ America/New_York:  2025-08-18 02:53:20 (UTC-4)
→ Asia/Tokyo:        2025-08-18 15:53:20 (UTC+9)

This tool uses the browser's native Date object and Intl.DateTimeFormat for the conversions — no external libraries, no server calls.

Frequently asked questions

What exactly is a Unix timestamp?

It's the number of seconds elapsed since January 1, 1970 00:00:00 UTC (the "Unix epoch"), independent of timezones and leap seconds.

Does it work with seconds or milliseconds?

Both: there's a toggle to say whether the timestamp you pasted is in seconds (Unix standard, ~10 digits) or milliseconds (used by JavaScript, ~13 digits).

How does it handle timezones?

A Unix timestamp is always the same absolute instant in time; the timezone only changes how that instant is displayed. You can pick any IANA zone (e.g. America/Argentina/Buenos_Aires) to see the corresponding local date.

Is the date-to-timestamp conversion accurate with timezones?

Yes for the vast majority of cases. It uses the browser's native Intl APIs; right at a daylight-saving transition there can be a one-hour ambiguity, which is inherent to how civil calendars work, not a bug in the tool.