What Is a Unix Timestamp?
A Unix timestamp is a single number that represents a specific moment in time. It counts the number of seconds that have elapsed since the Unix epoch — midnight (00:00:00) on 1 January 1970, in Coordinated Universal Time (UTC). Because it is just a plain integer, it is the same everywhere on the planet at any given instant, which makes it the global standard for storing and exchanging dates in software, databases, log files, and APIs.
This converter takes that raw number and turns it into a human-readable date and time, showing the result in UTC alongside major cities such as New York, London, Tokyo, and Sydney so you can see exactly what the same instant looks like around the world.
How to Use the Converter
- Enter your Unix timestamp into the input field (for example, 1700000000).
- Confirm whether your value is in seconds or milliseconds — most timestamps are in seconds, but JavaScript and some APIs use milliseconds (13 digits instead of 10).
- Read the converted date and time in UTC, then compare it across the listed time zones.
The Formula Explained
To turn a timestamp into a readable date, you add the number of seconds to the epoch:
Date = 1 January 1970 00:00:00 UTC + (timestamp seconds)
To convert any local time back into a timestamp, you measure the seconds between that moment and the epoch. Time zones do not change the timestamp itself — they only shift how the same instant is displayed. New York in winter is UTC−5, London is UTC+0, Tokyo is UTC+9, and Sydney is UTC+10 or +11 during daylight saving.
Worked Example
Take the timestamp 1700000000. Adding that many seconds to the epoch gives 14 November 2023, 22:13:20 UTC. The same instant is 17:13:20 in New York, 22:13:20 in London, and 07:13:20 the next morning in Tokyo.
Frequently Asked Questions
Why does my timestamp look 1,000× too big? It is probably in milliseconds. Divide by 1,000 to get seconds.
Does the timestamp account for time zones? No. A Unix timestamp is always based on UTC. The displayed local times are just different views of one universal moment.
What is the year 2038 problem? Systems storing timestamps as 32-bit integers will overflow on 19 January 2038. Modern 64-bit systems avoid this entirely.
