Unix Timestamp Converter

A Unix timestamp (also called epoch time or POSIX time) is simply the number of seconds that have passed since 1970-01-01 00:00:00 UTC, the moment known as the epoch. Because it is one plain number, it is easy to store, sort and subtract, which is why logs, databases and API responses use it instead of a written-out date. The number 1720512345, for example, is roughly 54 years' worth of seconds after the epoch. Times before 1970 are written as negative numbers, and this Unix timestamp converter handles those too.

A 10-digit timestamp counts seconds; a 13-digit one counts milliseconds and is exactly 1000 times bigger. That is why the same instant is 1720512345 in Python or PHP but 1720512345678 in JavaScript's Date.now() or Java's System.currentTimeMillis(). A 16-digit number is usually microseconds, common in Postgres and Python's time_ns()/1000. The quick rule: 10 digits = seconds, 13 = milliseconds, 16 = microseconds. This epoch converter counts the digits for you, shows which unit it detected, and lets you override the guess with the Unit selector if your data is unusual.

No. A timestamp is a single moment counted from the UTC epoch, so it carries no time zone at all — the same number means the same instant everywhere on Earth. A time zone only appears when you display it: 1720512345 is 09:25 in Seoul and 00:25 in London on the same day. That is why this converter always shows your local time and UTC side by side. If a converted date looks a few hours off, the timestamp is not wrong; you are most likely comparing a UTC reading with a local one.

Systems that store Unix time in a signed 32-bit integer run out of room at 03:14:07 UTC on 19 January 2038 (timestamp 2147483647), and the counter can wrap around to 1901 — the reason it is called the Y2K38 problem. It affects old C programs and embedded devices, not this tool: your browser keeps the value as a 64-bit floating point number, so this converter works from about 275,760 BC to AD 275,760 (±8.64e15 milliseconds). Anything beyond that range gets an explicit out-of-range message rather than a wrong date.

No. Every conversion runs inside your browser with the built-in Date and Intl features — there is no API call, no analytics on your input, and nothing is uploaded or logged. The page also stores nothing about your conversions: the timestamp and unit you choose live only in the open tab and disappear when you close it. That means production log data or customer timestamps are safe to paste here, and the converter keeps working offline once the page has loaded.