What is an OUI?
The first 3 bytes (24 bits) of a MAC address are its OUI (Organizationally Unique Identifier), assigned by the IEEE Registration Authority to one specific manufacturer. Two smaller registries exist for organizations that need fewer addresses: MA-M (28-bit prefix) and MA-S (36-bit prefix). This tool looks up all three, trying the most specific (longest) match first.
| Registry | Prefix length | Entries in this tool |
|---|---|---|
| MA-L (traditional OUI) | 24 bits (6 hex digits) | 40,253 |
| MA-M (OUI-28) | 28 bits (7 hex digits) | 6,606 |
| MA-S (OUI-36) | 36 bits (9 hex digits) | 7,205 |
Data downloaded 2026-09-27 from the public IEEE registries: oui.csv, mam.csv, oui36.csv. 54,064 entries total, shipped as 256 compact JSON shards (6,090 KB) split by first byte, so a lookup only ever downloads the one shard it needs.
Unicast/multicast and universal/local: the two address bits
The first byte of a MAC address carries two flag bits, independent of which vendor (if any) it belongs to:
| Example | First byte | Unicast/multicast | Universal/local |
|---|---|---|---|
00:DB:70:12:34:56 (Apple, factory-assigned) | 00 | Unicast | Universal |
01:00:5E:00:00:01 (IPv4 multicast base) | 01 | Multicast | Universal |
02:1A:2B:3C:4D:5E (randomized/local example) | 02 | Unicast | Local |
A real device's own MAC address is essentially always unicast (multicast addresses are destinations for groups of listeners, not a NIC's own identity). Locally administered addresses -- recognizable by a second hex digit of 2, 6, A or E -- are assigned by software rather than burned in by a manufacturer, which is why modern phones, laptops and VMs using randomized or virtual MACs never have a vendor match here.
Finding your own MAC address
| OS | Where to look |
|---|---|
| Windows | ipconfig /all in Command Prompt, or Settings → Network & Internet → your connection → Properties |
| macOS | System Settings → Wi-Fi/Network → Details → Hardware, or ifconfig en0 | grep ether in Terminal |
| Linux | ip link show or ifconfig -a in a terminal |
| iPhone/iPad | Settings → General → About → Wi-Fi Address (usually a randomized "private" address) |
| Android | Settings → About phone → Status → Wi-Fi MAC address |
Privacy: what this tool sends over the network
Everything you type is parsed and matched entirely in your own browser. The only network request is for a small JSON file containing every vendor assigned to your MAC's first byte (e.g. /oui/00.json for any address starting 00:) -- the same file every visitor looking up any address in that range would fetch. That request reveals 1 of the address's 6 bytes; the full address is never transmitted or logged.
Frequently asked questions
What is an OUI?
An Organizationally Unique Identifier: the first 3 bytes (24 bits) of a MAC address, assigned by the IEEE Registration Authority to a specific manufacturer (e.g. Apple, Cisco, Samsung). Two smaller, newer blocks exist too -- MA-M (28-bit) and MA-S (36-bit) -- for organizations that need fewer addresses than a full 24-bit OUI provides. This tool's data (downloaded 2026-09-27) has 40,253 MA-L, 6,606 MA-M and 7,205 MA-S entries -- 54,064 total.
How do I find my MAC address on Windows?
Open Command Prompt and type ipconfig /all -- look for "Physical Address" under your active network adapter (Wi-Fi or Ethernet). Or: Settings > Network & Internet > [your connection] > Properties, and look for "Physical address (MAC)".
How do I find my MAC address on macOS?
System Settings > Wi-Fi (or Network) > Details > Hardware, or open Terminal and type ifconfig en0 | grep ether (en0 is usually Wi-Fi; try en1 for Ethernet on some Macs).
How do I find my MAC address on Linux?
Open a terminal and type ip link show or ifconfig -a -- the address next to "link/ether" (ip) or "ether" (ifconfig) is the MAC address for each network interface.
How do I find my MAC address on iPhone or Android?
iPhone: Settings > General > About > Wi-Fi Address (this is normally a randomized, "private" address -- see below). Android: Settings > About phone > Status (or Wi-Fi settings > the connected network's details) > Wi-Fi MAC address.
Why does this tool show "no vendor match" for my phone or laptop's MAC?
Modern phones, laptops and tablets (iOS 14+, Android 10+, Windows 10+, most current versions) use a randomized, "locally administered" Wi-Fi MAC address by default for privacy -- a different, made-up address for each network you join, which was never assigned to any manufacturer and will never be in this or any vendor database. You can tell: its second hex digit is 2, 6, A or E (like 02:1A:2B:3C:4D:5E, shown above with the "locally administered" flag set). The vendor lookup only works for a device's original, factory-assigned ("universally administered") MAC.
What's the difference between unicast and multicast?
The least-significant bit of the first byte: 0 means the address identifies a single device (unicast, the normal case for a device's own MAC); 1 means it's a multicast/broadcast group address that a group of devices all listen for (e.g. 01:00:5E:00:00:01, the base of the IPv4 multicast range, shown above). A real device's own MAC is always unicast; you'd only see a multicast flag on a destination address inside a captured packet, not on hardware.
What's the difference between universally and locally administered?
The second-least-significant bit of the first byte: 0 means "universally administered" -- burned into the hardware by the manufacturer from their IEEE-assigned OUI, and lookupable here. 1 means "locally administered" -- assigned by software instead (randomized Wi-Fi MACs, virtual machine/container network interfaces, VPN adapters) and never in a vendor registry, no matter how complete.
Is my MAC address uploaded when I look it up here?
Only partially, unavoidably: this tool fetches a small JSON file containing every vendor assigned to your MAC's first byte (e.g. every OUI starting with 00 fetches the same /oui/00.json used by every visitor looking up any 00:xx:xx:xx:xx:xx address) and looks up your exact address locally in your browser -- so the request that leaves your device reveals only 1 of the address's 6 bytes, and it's the same request anyone else with a same-first-byte MAC would make. The full address is never sent anywhere.
How current is this data, and can I get an update?
Downloaded 2026-09-27 directly from the IEEE's own public registries. IEEE updates these continuously as new OUIs are assigned; this site refreshes its copy periodically. If a very recently assigned OUI doesn't show a vendor, that's the most likely reason.