Unix Timestamp Converter

What is a Unix Timestamp?

A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC, not counting leap seconds. This date is known as the Unix epoch. Unix timestamps are widely used in programming, databases, and APIs because they represent a single, unambiguous point in time regardless of timezone.

For example, the timestamp 1700000000 represents November 14, 2023 at 22:13:20 UTC. Timestamps can be in seconds (10 digits) or milliseconds (13 digits). JavaScript’s Date.now() returns milliseconds, while most Unix systems use seconds.

Unix Time vs UTC vs ISO 8601

Unix time is a plain number counting seconds from the epoch. UTC (Coordinated Universal Time) is the global time standard used as the reference point. ISO 8601 is a human-readable date format (e.g., 2023-11-14T22:13:20Z) commonly used in APIs and data exchange. All three represent the same moment in time — just in different formats.

Frequently Asked Questions

What is a Unix timestamp?

A Unix timestamp is the number of seconds elapsed since January 1, 1970 00:00:00 UTC (the Unix epoch). It is a universal way to represent a point in time as a single integer, used by virtually all programming languages and operating systems.

What is epoch time?

Epoch time is another name for Unix time. The “epoch” refers to the starting point — January 1, 1970 00:00:00 UTC. Any Unix timestamp counts the seconds (or milliseconds) from this epoch.

How do I convert a timestamp to a date in JavaScript?

Use new Date(timestamp * 1000) for a seconds-based timestamp, or new Date(timestamp) for milliseconds. The Date object then provides methods like .toISOString() and .toLocaleString() to format the result.

What is the Year 2038 problem?

The Year 2038 problem occurs because many systems store Unix time as a 32-bit signed integer, which can hold a maximum value of 2,147,483,647 — corresponding to January 19, 2038 at 03:14:07 UTC. After that moment, the counter overflows. Modern 64-bit systems are not affected.

What is the difference between seconds and milliseconds timestamps?

A seconds timestamp has 10 digits (e.g., 1700000000) and counts whole seconds since the epoch. A milliseconds timestamp has 13 digits (e.g., 1700000000000) and offers higher precision. JavaScript uses milliseconds; most Unix commands use seconds. This converter auto-detects the format.