What MAC address formats does MACLookup accept?

The separators may be :, -, ., a space, in any mix, or absent entirely. The lookup removes them and matches on the hexadecimal digits, so it needs at least 6 of them and accepts either case. Input longer than six digits is accepted too: only the first six are matched, which is what lets a full address and a bare prefix be searched the same way.

Six-digit prefix notations

  • 001A2B
  • 00:1A:2B
  • 00-1A-2B
  • 001A.2B

Full address notations

  • 001A2B3C4D5E
  • 00:1A:2B:3C:4D:5E
  • 00-1A-2B-3C-4D-5E
  • 001A.2B3C.4D5E
  • 00.1A.2B.3C.4D.5E

Every notation above was submitted to the lookup and returns the same prefix, 001A2B. Separators may be mixed within one value; nothing requires the same character throughout.

Why six digits is the minimum

The shortest assignment the IEEE issues fixes 24 bits, three octets, six hexadecimal digits. Shorter input cannot match any registered block, so it is rejected as a bad format rather than answered with an empty result — the two outcomes mean different things, and why a lookup returns no vendor separates them.

Longer input is not rejected. A twelve-digit address is matched on its first six digits, which is why searching a full address returns the organization of the block it belongs to rather than a per-device record: no per-device registry exists. How a lookup works covers the prefixes it tests.

What is not accepted

  • Any character outside the hexadecimal range after the separators are removed. A stray character from a copy-paste is reported as a bad format.
  • Fewer than 6 hexadecimal digits, including an empty value and a lone separator.

Where the list comes from

The accepted set is defined once in the application and rendered by both the API documentation and the LLM text files, so the page you are reading, the API reference and the API itself cannot state different rules. To send one of these notations programmatically, see the free lookup API.

Related questions

Sources and review

Last reviewed: . Technical claims on this page follow the primary sources below; operating-system interfaces change between releases, so check them against your own device version.