Is my timestamp sent anywhere?

No. The conversion happens entirely in your browser using the built-in JavaScript Date object. Nothing is uploaded to any server.

What is the difference between seconds and milliseconds?

Unix time is most often counted in seconds since 1 January 1970 UTC, but JavaScript and many APIs use milliseconds (1000× larger). Use the dropdown to tell the converter which unit your number is in.

Why does my local time differ from UTC?

UTC is the global reference time with no offset, while local time is shifted by your time zone and daylight saving. The tool shows both so you can compare them directly.

What is a Unix timestamp?

It is the number of seconds (or milliseconds) that have elapsed since the Unix epoch, midnight UTC on 1 January 1970, ignoring leap seconds. It is the standard way computers store an instant in time independent of time zone.

How do I tell if a number is in seconds or milliseconds?

A present-day timestamp in seconds is about 10 digits (around 1.7 billion), while the same instant in milliseconds is about 13 digits. Pick the matching mode, or as a rule of thumb a 13-digit value is almost always milliseconds.

What is the year 2038 problem?

Systems that store Unix time in a signed 32-bit integer overflow on 19 January 2038, when the value exceeds 2,147,483,647 seconds. Modern systems use 64-bit timestamps, which push the limit hundreds of billions of years into the future.

Does the timestamp 0 mean anything special?

Yes — Unix timestamp 0 is exactly the epoch: 00:00:00 UTC on 1 January 1970. Negative values represent dates before 1970.

Why do I see 1 January 1970 when I expected a recent date?

That usually means a milliseconds value was read as seconds (or a value of 0 or null was passed). A small number of seconds since the epoch lands in early 1970, so check that you selected the right unit.

Unix Timestamp Converter

Unix timestamp converter

A Unix timestamp (also called epoch time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, the moment known as the Unix epoch. It is the most common way software stores an instant — in databases, log files, API responses and JWT tokens — because it is a single number free of time zones. This converter turns epoch values into readable dates and converts any date back into a timestamp, all in your browser.

How it works

Enter an epoch value and choose seconds or milliseconds. The tool multiplies seconds by 1000 to build a JavaScript Date, then formats it four ways: the UTC time (no offset), your local time (shifted by your time zone and daylight saving), the ISO 8601 string (e.g. 2021-01-01T00:00:00.000Z), and a relative label such as “3 hours ago” or “in 2 days”. The reverse direction takes a date and time from the picker and reports the matching epoch seconds and milliseconds.

Example

The timestamp 1609459200 in seconds is 1609459200 × 1000 milliseconds, which the Date object resolves to 2021-01-01T00:00:00.000Z — midnight UTC on New Year’s Day 2021. Read as milliseconds instead, the same digits would point to 19 January 1970, which is why selecting the correct unit matters.

Value	Unit	Resolves to (UTC)
0	seconds	1970-01-01 00:00:00
1609459200	seconds	2021-01-01 00:00:00
1609459200000	milliseconds	2021-01-01 00:00:00

Everything runs in your browser using the built-in Date object — nothing you type is ever uploaded.