Network · Developer
MAC address validator.
Paste a MAC address in any common format — colon, hyphen, Cisco dotted or bare hex, 48-bit or 64-bit. Get it back in every format, with the unicast/multicast and universal/local bits decoded. Checks format only; nothing leaves your browser.
MAC address
Result
Enter an address, then press Validate.
MAC address formats
The same 48 bits are written several ways. Colon (00:1A:2B:3C:4D:5E) is common on Linux and macOS. Hyphen (00-1A-2B-3C-4D-5E) is the form the IEEE Registration Authority calls the hexadecimal representation, and is what Windows prints. Dotted (001A.2B3C.4D5E) is the Cisco convention, three groups of four digits. Bare (001A2B3C4D5E) is the IEEE base-16 form with no separators. An EUI-64 is the same idea with 16 hex digits.
What the first octet tells you
When an EUI is used as a MAC address, the two least significant bits of the first octet are special. The I/G bit (bit 0) is 0 for an individual (unicast) address and 1 for a group (multicast) address. The U/L bit (bit 1) is 0 for a universally administered address, meant to be globally unique, and 1 for a locally administered one. Example: first octet AC is 10101100, so I/G=0 and U/L=0.
Broadcast: FF:FF:FF:FF:FF:FF is the all-stations group address. The IEEE notes it is not a valid EUI. All-zero values are also not used as identifiers.
Source: IEEE Registration Authority, Guidelines for Use of EUI, OUI, and CID (2017-08-03), read 2026-09-30. The dotted form is a vendor convention, not an IEEE form.
Frequently asked questions
Does "valid" mean the address belongs to a real device?
No. This tool checks that the text is a well-formed 48-bit or 64-bit hex address and decodes its bits. It cannot tell whether the address was ever assigned, is in use, or belongs to any device.
Why is there no manufacturer lookup?
A vendor name needs the current IEEE registry, which changes constantly. Rather than ship a stale table, this tool leaves the vendor out. You can search the registry directly at the IEEE Registration Authority.
Why does my phone show an address with the U/L bit set?
A locally administered address is not tied to a manufacturer. Virtual machines, containers and randomised (private) Wi-Fi addresses commonly use them.
Format check only
This confirms the format and decodes the address bits. It does not confirm the address was issued to anyone. Everything runs in your browser and nothing you type is sent to any server.