MAC address lookup: vendor, format and address type
Paste a hardware address into this MAC address lookup and it tells you which company the address block was assigned to, using the public listings of the IEEE Registration Authority — the body that hands out the first half of every factory-assigned MAC address. It also rewrites the address in every common notation, decodes the two flag bits that say whether the address is unicast or multicast and whether it was set by the manufacturer or by software, and builds the matching IPv6 interface ID.
It is handy for identifying an unknown device in a router’s client list or an arp -a table, converting addresses between Cisco, Windows and Linux formats, cleaning up an inventory spreadsheet, or working out why a phone shows a different MAC address on every Wi-Fi network. Paste a whole list for a bulk lookup with CSV export. Everything runs in your browser; only the vendor list itself is downloaded.
How to use the MAC Address Lookup
- Type or paste a MAC address in “MAC address — or a list, one per line”. Any separator works, and so does a modified EUI-64 IPv6 address such as fe80::21a:2bff:fe3c:4d5e.
- Read the vendor under the large address, then the Formats card for colon, hyphen, Cisco dot and bare-hex versions.
- Check “Address type” for the I/G (unicast or multicast) and U/L (universal or local) bits, with an explanation for randomised and special addresses.
- For many addresses, paste the whole list or command output. A table appears with vendor, type and block for each address.
- Use “Copy all details”, “Download CSV” or “Copy as text” to take the results elsewhere.
MAC Address Lookup features
IEEE vendor list
MA-L, MA-M, MA-S and the older IAB assignments, matched from the most specific block down, so a 28-bit or 36-bit sub-assignment is found instead of the IEEE parent block.
Every notation
Reads and writes 00:1A:2B:3C:4D:5E, 00-1A-2B-3C-4D-5E, 001a.2b3c.4d5e, 001A2B3C4D5E and leading-zero-free forms like 0:1a:2b:3c:4d:5e from macOS.
Randomised MAC detection
Locally administered addresses are recognised and explained, including the IEEE 802c quadrant, Docker and QEMU/KVM conventions.
Special addresses
Broadcast, IPv4 and IPv6 multicast mappings, STP, LACP, LLDP, 802.1X, Cisco CDP, VRRP and HSRP virtual router MACs.
EUI-64 both ways
MAC to modified EUI-64 interface ID and link-local address, and back from an IPv6 address to the MAC it was built from.
How a MAC address is built
An EUI-48 MAC address is six bytes. In a factory-assigned address the first three bytes are the OUI (organizationally unique identifier) the IEEE sold to the manufacturer, and the manufacturer numbers its devices with the rest. Two bits of the first byte have special meanings: bit 0, the I/G bit, is 1 for multicast and broadcast group addresses; bit 1, the U/L bit, is 1 when the address was set locally by software rather than burned in by the maker.
So the second hex digit tells you a lot at a glance. If it is 2, 6, A or E (as in DA-A1-19-…), the address is locally administered and will never appear in the IEEE registry — exactly what phones do when they hide their real address.
| IEEE block | Prefix length | Addresses in the block |
|---|---|---|
| MA-L (MAC Address Block Large, the classic OUI) | 24 bits | 16,777,216 |
| MA-M (Medium) | 28 bits | 1,048,576 |
| MA-S (Small; replaced the IAB) | 36 bits | 4,096 |
| IAB (Individual Address Block, no longer issued) | 36 bits | 4,096 |
Why your phone shows a different MAC address
To stop Wi-Fi networks and shops tracking people, current versions of iOS, iPadOS, Android and Windows can use a randomised private address for each network instead of the hardware address. These set the U/L bit, so a vendor lookup correctly returns nothing. If a router lists an unknown device with such an address, compare it with the Wi-Fi details screen on your own devices — the private address is shown there.
IEEE 802c defines an optional scheme for local addresses, the Structured Local Address Plan (SLAP), which splits them into four quadrants by the second hex digit: 2 for administratively assigned, 6 reserved, A for extended local identifiers built on an IEEE Company ID, and E for standard assigned identifiers. Many randomised addresses ignore it, so treat the quadrant as a hint.
Where the vendor data comes from
The vendor list is a compact copy of the IEEE Registration Authority public listings, downloaded on 13 October 2026. The IEEE has stated that it does not assert copyright in the public listing or restrict its distribution, while encouraging users to fetch fresh copies from the IEEE directly — check the IEEE’s own search for assignments made after that date. Some companies pay for a private listing, in which case only “Private” is published. To analyse an IPv6 address built from a MAC, use the IP Address Parser; to see the details of your own connection, try My Browser Info.
MAC Address Lookup FAQ
How do I find the manufacturer of a device from its MAC address?
Paste the address into the MAC address lookup. The first 24, 28 or 36 bits are matched against the IEEE registry, and the company that owns that block is shown with its country. The result is the maker of the network chip or device, which is usually — but not always — the brand on the box.
Why does the lookup say “locally administered”?
The U/L bit in the first byte is set, which means software chose the address instead of the manufacturer. Randomised Wi-Fi addresses, virtual machines, containers, VPN adapters and bonded interfaces all do this, so there is no vendor to find.
Can a MAC address reveal someone’s location or identity?
No. It identifies a network interface on the local network, and it is not transmitted beyond the first router. The vendor tells you only who made the hardware.
What is the Cisco format of a MAC address?
Cisco switches and routers write MAC addresses as three groups of four hex digits separated by dots, such as 001a.2b3c.4d5e. The Formats card converts to and from this notation.
Is it safe to paste MAC addresses here?
Yes. The addresses are processed in your browser and never uploaded. The page downloads the public vendor list from this site once and reuses it for every lookup.
How is a MAC address turned into an IPv6 address?
Stateless address autoconfiguration can build a 64-bit interface ID by inserting FF:FE in the middle of the MAC and flipping the U/L bit (modified EUI-64, RFC 4291). 00:1A:2B:3C:4D:5E becomes the link-local address fe80::21a:2bff:fe3c:4d5e.