MAC vendor lookup

PUB 2026-07-20UPD 2026-10-27VERIFY Standards and official sources

// DATA As of 2026-10-16 IEEE Registration Authority (MA-L · MA-M · MA-S · IAB · CID) 59,003 entries + 37 entries from standards and vendor documentation Lookup data not yet loaded

APP $ mac-oui ✓ Runs entirely in your browser. The MAC address you enter is not sent to a server. The lookup table is loaded once from this site and used only in your browser.

Use the prefix of a MAC address (such as an OUI) to look up its assignee. Check unfamiliar addresses in a switch MAC address table or ARP cache, but do not treat the result as proof of the actual hardware manufacturer. Enter all 6 bytes to identify MA-M, MA-S, or IAB assignees and convert the address to all three formats.

Data The complete allocation lists from the IEEE Registration Authority are included: MA-L · MA-M · MA-S · IAB · CID, totaling 59,003 entries. The longest matching prefix takes precedence (MA-S/IAB: 9 hex digits → MA-M: 7 → MA-L/CID: 6). For information missing from the IEEE lists or not explained by the IEEE registrant name alone, we provide 37 additional entries based on standards (RFC and IEEE) and vendor documentation. Each entry cites its source. For example, 08:00:27 is registered with IEEE to PCS Systemtechnik GmbH, but is used by VirtualBox. These two layers of information do not replace each other. If an address is not listed, we report that without guessing. Locally administered addresses, such as randomized smartphone MAC addresses, may not reveal the manufacturer from the address alone.

MAC address (full address or first 3 bytes) Colons, hyphens, dots (Cisco format), and no separators are all accepted. You can look up a prefix using only its first 6 hex digits, such as 005056. To identify an MA-M, MA-S, or IAB assignee, enter the full 6-byte address (12 hex digits).

Options Show results in uppercase

Test examples — Click to try

00:50:56:AA:BB:CC 02:00:00:11:22:33 01:00:5E:00:00:01 0050.56aa.bbcc 08:00:27:12:34:56 52:54:00:AB:CD:EF

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Start here This card lists everything included with this tool. The data was retrieved on 2026-10-16 from the IEEE Registration Authority (IEEE source last updated: 2026-10-16T04:01Z). If an address is not listed, we report that without guessing. Address classification and notation conversion do not depend on the database: they are calculated from the address bits, so they also work for addresses that are not listed.

Calculated results, not lookup data (available even before the table loads)

Item	Derived from	Value	Explanation

Where the data comes from — Sources and record counts

Source	Content	Records	Prefix length

Search by vendor name, prefix, or description (all IEEE records: 59,003 entries; leave blank to browse all pages) Showing all records. Enter text to filter them.

IEEE allocations — 59,003 entries (use search to find a record)

Per page —

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Excel export is available only after you filter the data with a search. Enter at least 2 characters to enable it. There is no option to export the entire unfiltered list. The file contains all matching records across all pages, not just the page you are viewing.

Prefix	Assignee	Registry	Example address

Using this tool

When it helps

Use this tool when an unfamiliar address appears in a switch MAC address table or ARP cache and you want to check which organization received its prefix. The result offers a clue to compare with your asset inventory, but it does not identify the physical device by itself. First retain the port, address, and observation time from the original table.

It also helps normalize MAC notation copied from different devices or check whether an address is unicast or locally administered. Enter all 6 bytes to see prefix lookup and three notation formats together. In DATA, search the registration records by name or prefix to examine the source behind a result.

Understanding results

OUI (first 3 bytes) displays the first 3 bytes. Assignee / purpose can contain an IEEE registration name, registry, and prefix, or a use documented by a standard or vendor. Distinguish those sources. A full address can match a longer prefix, so a name associated with the first 3 bytes alone may not be the final answer.

Administration (U/L bit) and Delivery type (I/G bit) interpret those two bits. A universally administered indication does not mean the tool checked for duplicate addresses or authenticated a device. Colon, hyphen, and dotted notation represent the same address. Changing the uppercase option changes neither the address value nor the assignee.

A table not yet loaded, a failed table load, and no match in a loaded table are different states. Check the DATA reference date and loading status first. Bit classification and notation conversion work without the table, so a converted address does not establish that the registration lookup has completed.

Measured case

Entering 02:00:00:11:22:33 produced locally administered, U/L 1, unicast, I/G 0, and no entry in the lookup table. Hyphen notation was 02-00-00-11-22-33, and dotted notation was 0200.0011.2233. This demonstrates that a registration lookup and a calculation from address bits answer different questions.

Entering 01:00:5E:00:00:01 produced the use IPv4 all hosts on this link and multicast with I/G 1. U/L was 0, and dotted notation was 0100.5E00.0001. That describes a group use, not the name of a manufacturer of an individual device.

Questions and answers

Can I enter only the first 3 bytes?

The input accepts the first 3 bytes as 6 hexadecimal digits. However, enter all 6 bytes to identify assignments using longer prefixes, including MA-M, MA-S, and IAB. With only a prefix, the tool does not invent the missing bytes or produce dotted notation.

Can a locally administered address still show a name?

A documented use in a standard or virtualization product may appear as a reference. That differs from an IEEE assignment to the manufacturer of the device. A name attached to a randomized or manually chosen MAC address cannot establish the actual manufacturer.

What should I check if the table fails to load?

Check the network and data status message before reloading the page. Do not interpret a failed download as an unregistered address. Bit classification and notation conversion require different information from searching the registration records.

Does Excel export save only the visible page?

It saves matching IEEE rows across all pages. Enter at least 2 search characters and obtain matching results to enable the function. Exporting the complete unfiltered list in one operation is not provided.

Further details

How it operates

The tool removes colons, hyphens, dots, and whitespace, then checks for 6 or 12 hexadecimal digits. Other characters or an incorrect length produce an input error. The least significant bit of the first byte is I/G, and the next bit is U/L. Their classifications are calculated without consulting a vendor table.

Editing the address, choosing an example, or clicking a DATA tab loads the lookup table from this site. The entered MAC address is compared against that table in the browser rather than sent to a lookup server. For a full address, the tool checks 9-digit, 7-digit, then 6-digit prefixes. Multiple registrations for the same prefix appear together.

Standards and references

The IEEE Registration Authority supplies the registration basis for MA-L, MA-M, MA-S, IAB, and CID. MA-L, MA-M, and MA-S have assigned prefixes of 24, 28, and 36 bits respectively. A CID identifies a company but does not provide an assignment for generating universally unique MAC addresses, so it is not interchangeable with those address blocks.

The linked RFC 7042 describes IANA management of Ethernet numbers and documentation addresses; RFC 9542 now replaces it. IANA Ethernet Numbers records special address uses. Follow the individual sources in the standards and conventions entries and keep those uses distinct from an IEEE registration name.

Constraints

The tool does not investigate whether an address is active, which port it uses, or who owns the device. Spoofed, changed, and randomized addresses can be analyzed if their input format is valid. Assignments made after the data reference date or private registrations may not reveal a name. A missing result alone does not establish an intrusion or faulty equipment.

Standards: IEEE Registration Authority (MA-L, MA-M and MA-S assignments) · RFC 7042 (IANA considerations for Ethernet numbers) · IANA Ethernet Numbers (special addresses)