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MAC Address Tool

Reformat and validate MAC addresses; analyze local/unicast bits.

What MAC Address Analysis Does

A MAC address is a 48-bit (12 hex digit) hardware identifier assigned to a network interface. Vendors and operating systems write it differently, with colons (00:1A:2B:...), hyphens (00-1A-2B-...), or Cisco-style four-digit dots (001a.2b3c...), so you frequently need to reformat one when moving between device configurations.

This tool accepts a MAC address regardless of its separators and normalizes it into four formats: colon, hyphen, dot, and plain hex. At the same time it extracts the OUI (the first three bytes, identifying the vendor) and inspects the two least-significant bits of the first byte to tell you whether the address is unicast or multicast and whether it is universally (globally unique) or locally administered.

All parsing and analysis happen in your browser and the MAC you enter is never sent to a server, so real device addresses stay on your machine.

How to Use

  1. Type a MAC address into the input field. Separators can be colons, hyphens, dots, or none at all, as long as there are 12 hex digits.
  2. Read the four notations (colon, hyphen, dot, plain hex) and the OUI from the result card.
  3. Check the unicast/multicast and universal/local results as well, then copy whichever notation you need into your device config.

Frequently Asked Questions

What is the OUI and why does it matter?
The OUI (Organizationally Unique Identifier) is the first three bytes of a MAC, a vendor code the IEEE assigns to manufacturers. It lets you infer which company built an interface, which is useful for network inventory and troubleshooting.
How are unicast and multicast distinguished?
If the least-significant bit of the first byte (the I/G bit) is 0 the address is unicast (a single target); if it is 1 it is multicast (a group target). This tool inspects that bit automatically, and the broadcast address FF:FF:FF:FF:FF:FF is classified as multicast.
What is the difference between universal and local?
If the second bit of the first byte (the U/L bit) is 0 the address is a globally unique, manufacturer-assigned address (universal); if it is 1 it was set by an administrator (local). Virtual machines and MAC randomization features typically use locally administered addresses.