Unix Timestamp Converter

What the Unix timestamp converter does

This handles epoch time both ways in one place. Give it a Unix timestamp and it shows you the readable date and time; give it a date and time and it produces the timestamp. When it decodes a timestamp, it shows both the GMT version and your local version together, so you can read the moment in the neutral reference and in your own zone at a glance. It is the all-rounder for working with epoch values.

How to use it

1. Pick a direction. Timestamp to Date and Time, or Date and Time to Timestamp.
2. For a timestamp. Enter the number and convert.
3. For a date. Enter the year, month, day, and time, and choose whether your input is Local time or GMT.

Press Convert for the result.

What a Unix timestamp is

A Unix timestamp, also called epoch or POSIX time, is the number of seconds since one fixed moment: midnight UTC on the 1st of January 1970. It captures any instant as a single growing integer, which is why systems lean on it so heavily. Storing a time is storing one number, comparing two times is comparing two numbers, and the gap between them is just subtraction, no calendar maths required.

Both directions, and GMT next to local

The reason to have both directions in one tool is that real work needs both. You decode a timestamp from a log to see when something happened, and you encode a date into a timestamp to feed a query or set a value. The nice touch here is that when you decode, it gives you GMT and local side by side. Logs and servers almost always record time in GMT, which is the same as UTC for this purpose, but you usually think in your own local time, so seeing both at once saves you doing the offset in your head. And when you encode, telling it whether your input is local or GMT makes sure the number comes out right rather than being a few hours off.

Seconds, not milliseconds

Worth knowing to avoid the usual mix-up: this works in seconds, which is the classic Unix scale and a 10-digit number for the current era. Plenty of systems, JavaScript among them, count in milliseconds, which is a thousand times larger and runs to 13 digits. If a timestamp you decode lands absurdly far in the future, it is milliseconds, so divide by 1000. If you need milliseconds out of an encoded value, multiply by 1000.

Where it fits

General epoch work during development and debugging. Reading timestamps out of logs and databases, building timestamps to store or query, and checking values while you trace a problem across systems in different regions, where the GMT-and-local view is especially handy. If you only ever need one direction, a dedicated timestamp-to-date or date-to-timestamp tool is simpler, but this one covers the lot.

Questions people ask

Does it convert both ways?

Yes. A switch lets you go from a timestamp to a date or from a date to a timestamp, so you do not need a separate tool for each direction.

What is the difference between the GMT and local results?

GMT is the neutral reference, the same as UTC here, which is how servers usually record time. Local is that same moment shown in your own time zone. They are the same instant, written two ways.

Is it seconds or milliseconds?

Seconds, the standard Unix scale. If a decoded date is wildly in the future your input was milliseconds, so divide by 1000. Multiply an encoded result by 1000 if you need milliseconds.

Why does it ask if my date is local or GMT?

Because the same wall-clock date is a different moment depending on the zone. Telling it which one you mean keeps the resulting timestamp accurate instead of off by your zone's offset.

References

1. The Open Group, POSIX.1 Base Specifications, Base Definitions, "Seconds Since the Epoch." https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html