A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, not counting leap seconds. It is a simple, timezone-independent integer, which is why logs, databases, APIs and JWT "exp"/"nbf" claims store time this way.

By digit count. A current timestamp in seconds is about 10 digits (e.g. 1751800000), milliseconds is 13 digits, microseconds 16, and nanoseconds 19. This converter auto-detects the unit from the length of the number you paste, so you rarely have to pick one manually.

Paste the epoch number into the "Epoch to date" field. The tool detects the unit, then shows the moment in your local timezone, in UTC, and as ISO 8601, RFC 2822 and a relative "x ago" string. Every result has a copy button.

Use the "Date to epoch" field to pick a date and time (or paste an ISO string). The converter returns the value in both seconds and milliseconds, ready to copy. You choose whether your input is interpreted in local time or UTC.

A Unix timestamp itself has no timezone - it is an absolute point in time counted from the UTC epoch. Timezones only matter when you display it as a human-readable date. This tool shows the same instant side by side in your local zone, in UTC, and in any IANA timezone you select.

Systems that store the timestamp in a signed 32-bit integer can only count up to 2,147,483,647 seconds, which is reached at 03:14:07 UTC on 19 January 2038. After that the value overflows. Modern systems use 64-bit integers, which push the limit hundreds of billions of years into the future.

No. Every conversion runs entirely in your browser using the native Intl and Date APIs. No timestamps, dates or timezones are uploaded, logged or stored on a server.