Reformat any MAC address and decode its bits.

Paste a 48-bit MAC / EUI-48 address in any notation — colon-separated (00:1B:44:11:3A:B7), hyphenated (00-1B-44-11-3A-B7), Cisco dotted (001b.4411.3ab7) or bare hex (001B44113AB7) — and it re-emits every other notation at once, decodes the U/L and I/G bits, and derives the matching EUI-64 identifier. Everything is computed in your browser; nothing is uploaded.

No. Detection, parsing and formatting all run 100% client-side in your tab — there is no server, no account and no logging. You can safely paste hardware addresses from internal inventory.

It reads colon, hyphen, Cisco dot (xxxx.xxxx.xxxx) and bare-hex notations, in upper or lower case, and tolerates surrounding whitespace. It emits the colon, hyphen, Cisco dot and bare forms in both cases, so you can copy whichever your switch, hypervisor or config file expects.

They are the two least-significant bits of the first octet. The I/G bit (bit 0) is the individual/group flag: 0 is a unicast address, 1 is a multicast (group) address. The U/L bit (bit 1) is the universal/local flag: 0 means a globally unique, OUI-assigned address from the manufacturer, 1 means the address is locally administered — for example a randomised or virtual-machine MAC.

EUI-64 is the 64-bit interface identifier derived from a 48-bit MAC by inserting FF:FE in the middle and flipping the U/L bit. It is the historical way an IPv6 host built the host half of its address: prepend the fe80::/64 link-local prefix to that EUI-64 and you get the interface link-local IPv6 address. The formatter shows both the modified EUI-64 and the resulting fe80:: address.

Split the 48-bit MAC in half and insert FF:FE between the two halves to produce a 64-bit value. Then XOR the first octet with 0x02 to flip the U/L bit — this is the modified EUI-64 interface identifier. Prepend the fe80::/64 link-local prefix to get the full fe80:: address. The tool performs all three steps automatically and shows the compressed IPv6 result alongside every MAC notation.

Cisco IOS uses three groups of four lowercase hex digits separated by dots, for example 001b.4411.3ab7. The formatter strips any separators from the input, groups the twelve hex digits as four-digit triplets, and emits the Cisco dotted notation alongside the colon, hyphen and bare forms. No scripting or manual regrouping is needed.

The OUI (Organizationally Unique Identifier) is the first 24 bits — the first three octets — of a MAC address, assigned by the IEEE to identify the manufacturer or registrant. The formatter extracts and displays the OUI portion (for example 00:1B:44) so you can identify the vendor block. Full vendor-name resolution requires the complete IEEE database, which the tool does not include, but the OUI value itself is always shown.

A locally administered address is assigned by software or a network administrator rather than burned in by the hardware vendor. It is flagged by setting the U/L bit (the second-least-significant bit of the first octet) to 1, which means XORing the first octet with 0x02. Virtual machine NICs and randomised MAC addresses commonly use this flag. The formatter reads the U/L bit directly and labels the address either Universal / OUI-assigned or Locally administered.