Question 1

What is a Unix timestamp?

Accepted Answer

A Unix timestamp (also called Unix time or POSIX time) is the number of seconds that have elapsed since the Unix Epoch: January 1, 1970, 00:00:00 UTC. It is timezone-independent and universally used in databases, APIs, and programming languages to store dates as a single integer.

Question 2

What is the difference between seconds and millisecond timestamps?

Accepted Answer

Unix timestamps traditionally count seconds. JavaScript's Date.now() returns milliseconds (1,000× larger). When you see a 13-digit number like 1713100800000, it is milliseconds; a 10-digit number like 1713100800 is seconds. The converter handles both.

Question 3

Why is 1970-01-01 the Unix Epoch?

Accepted Answer

The date was chosen by the early Unix developers as a convenient reference point when designing the time representation for Unix Version 6. It had no deep significance — it was simply a recent, round date that kept timestamps as small positive numbers for the foreseeable future.

Question 4

What is the Year 2038 problem?

Accepted Answer

Many older 32-bit systems store Unix timestamps as a signed 32-bit integer, which overflows on January 19, 2038 at 03:14:07 UTC. Modern 64-bit systems are not affected. The converter uses JavaScript 64-bit floats, supporting dates well beyond the year 2038.

Question 5

How do I get the current Unix timestamp?

Accepted Answer

Click the "Use Now" button to populate both fields with the current time and its Unix timestamp. In code: JavaScript: Math.floor(Date.now()/1000), Python: import time; int(time.time()), PHP: time(), SQL: UNIX_TIMESTAMP(), Unix shell: date +%s.

Question 6

What is ISO 8601 format?

Accepted Answer

ISO 8601 is the international standard for representing dates and times (e.g. 2024-04-14T12:00:00.000Z). The "Z" suffix denotes UTC. It is sortable as a string, unambiguous, and widely supported by APIs, databases, and programming languages.

Question 7

Why does my converted date show the wrong time?

Accepted Answer

Timestamps are stored in UTC, but display in your local timezone. A timestamp of 1713100800 is April 14, 2024 12:00:00 UTC. In New York (UTC−4), this displays as 08:00:00 local time. The ISO 8601 output always shows UTC (ending in Z) to avoid timezone ambiguity.

Unix Timestamp Converter

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