Understanding UUID Version 1: A Unique Identifier Based on Time and Node ID

UUID version 1 (Universally Unique Identifier version 1) is a type of UUID that is based on time and node ID. It is defined in RFC 4122 as a UUID scheme that uses a timestamp and the MAC address (or other node identifier) of the computer generating the UUID to create a unique identifier.

The UUID version 1 is a 128-bit number represented by 32 hexadecimal digits, divided into five groups separated by hyphens in the following format:



  • x: represents a hexadecimal digit (0-9, a-f)
  • The first three groups (xxxxxxxx-xxxx-1xxx) indicate that this is a version 1 UUID. The fourth group (xxxx) has a fixed first hexadecimal digit, while the second can have one of four possible values, depending on the variant of the UUID (reserved, Microsoft, future, or random). The last group (xxxxxxxxxxxx) represents the 48-bit timestamp and the node identifier.

Here's an example of a UUID version 1:


To generate a UUID version 1 you can use our online tool available for free. Try to generate a UUID v1 using UUIDGen generartor.