Question 1

How do I convert a Unix timestamp to a readable date?

Accepted Answer

Paste your timestamp in the Epoch → Date tab above and click Convert. The tool auto-detects whether your timestamp is in seconds (10 digits) or milliseconds (13 digits) and shows the result in ISO 8601, UTC, and a friendly format for any timezone.

Question 2

What is the difference between Unix time in seconds and milliseconds?

Accepted Answer

A 10-digit timestamp (e.g. 1700000000) is in seconds. A 13-digit timestamp (e.g. 1700000000000) is in milliseconds. JavaScript's Date.now() returns milliseconds; most server-side languages (Python, PHP, Go) return seconds. Multiply by 1000 to convert seconds to milliseconds.

Question 3

How do I convert milliseconds to seconds?

Accepted Answer

Divide the millisecond timestamp by 1000. In JavaScript, use Math.floor(milliseconds / 1000) when you need whole Unix seconds. To convert seconds back to milliseconds, multiply by 1000.

Question 4

What is a 16-digit Unix timestamp?

Accepted Answer

A 16-digit Unix timestamp usually represents microseconds since the Unix epoch. Divide it by 1,000,000 to get seconds, or by 1000 to get milliseconds for JavaScript Date.

Question 5

What is the difference between Unix time and UTC?

Accepted Answer

Unix time is a count of seconds elapsed since a fixed reference point (1970-01-01 00:00:00 UTC). UTC is the time standard that defines that reference point. A Unix timestamp always represents the same moment in UTC regardless of your local timezone.

Question 6

Can a Unix timestamp be negative?

Accepted Answer

Yes. Timestamps before January 1, 1970 00:00:00 UTC are negative. For example, -86400 corresponds to December 31, 1969 00:00:00 UTC.

Question 7

What is the Year 2038 problem?

Accepted Answer

Legacy systems that store Unix timestamps as 32-bit signed integers will overflow on January 19, 2038 at 03:14:07 UTC (the maximum value is 2,147,483,647). Modern 64-bit systems are unaffected and can represent dates billions of years in the future.

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