How do I know if my timestamp is in seconds or milliseconds?

A 13-digit number is typically milliseconds, while a 10-digit number is typically seconds -- mixing them up gives a wildly wrong date, so it's worth checking the digit count before converting.

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Unix Timestamp Converter

Convert between Unix timestamps and human-readable dates

Files never stored

Unix Timestamp (seconds or ms)

Date / Time (UTC)

Human-readable (local time)

Mon Sep 21 2026 02:08:26 GMT+0000 (Coordinated Universal Time)

What is this tool?

Converts between Unix timestamps (the number of seconds since January 1, 1970) and human-readable dates, in either direction.

How to use it

Enter a timestamp or a date, and the other format updates automatically. A "use current time" button fills in the current timestamp instantly.

Watch whether your timestamp is in seconds or milliseconds — a 13-digit number is typically milliseconds, while a 10-digit number is typically seconds, and mixing them up gives a wildly wrong date.

Watch: Unix Timestamp Converter in Action

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Unix Timestamp Converter

What is this tool?

How to use it

Watch: Unix Timestamp Converter in Action

Frequently asked questions