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mac-address

How to find what device a MAC address belongs to

Updated July 13, 2026 2 min read
TL;DRA MAC address's first half is the manufacturer (OUI). Here's how to look up the vendor, narrow down the device, and why the answer is sometimes 'private'.

Short answer: the first three bytes of a MAC address are the manufacturer’s OUI. Look those up in a vendor database and you have the maker; the model follows from context.

The structure of a MAC address

A MAC address is six bytes, e.g. A4:83:E7:2C:1B:90:

  • A4:83:E7 — the OUI. Registered to one manufacturer (here, Apple).
  • 2C:1B:90 — the device-specific part, assigned by that manufacturer.

So the maker is deterministic; you just need a current OUI-to-vendor map. Run the address through a MAC vendor lookup to get it, or browse the OUI vendor directory to see how a prefix maps to an organization.

A worked example

Take 44:38:39:FF:EF:57. The OUI is 44:38:39, which the IEEE registered to Cumulus Networks — so this is networking hardware, not a phone. Now take DA:A1:19:5F:2C:88. The second hex digit is A, which means the locally-administered bit is set: this address was invented by the device for privacy, and no vendor lookup will resolve it. Two addresses, two completely different answers, and the difference is one bit.

From vendor to device type

The vendor narrows things fast:

  • Espressif / Texas Instruments / Realtek → a smart-home gadget or IoT board.
  • Apple / Samsung / Google → a phone, tablet, or watch (often randomized — see below).
  • Amazon → an Echo, Fire TV, or Kindle.
  • Sonos / Roku / LG → a speaker or TV.
  • Ubiquiti / TP-Link / Netgear → networking gear.

The model itself isn’t in the MAC — that’s an inference from the vendor plus context (what it is, when it connects, its hostname). If you’re resolving many addresses, for example across a whole router device list, the lookup API returns the vendor, the randomized flag, and a confidence score in one call.

When the OUI is “locally administered”

If the second-least-significant bit of the first byte is set, the address is locally administered — not a real vendor OUI. That’s a randomized MAC, and the vendor lookup can’t help. The full mechanics are in randomized MAC addresses, explained; the short version is in why devices hide their MAC. When you hit one, identify the device by hostname and elimination instead — see identifying an unknown device.

Frequently asked questions

What is an OUI in a MAC address?

The OUI (Organizationally Unique Identifier) is the first three bytes of a MAC address — a block the IEEE registers to a single manufacturer. It's how a MAC maps to a maker.

Can a MAC address tell me the exact device model?

Not by itself. The MAC reliably gives the manufacturer via the OUI. The specific model is an inference from the vendor plus context — the device type, when it connects, and its hostname.

Why does my MAC lookup return no vendor?

Either the address is randomized (a locally administered address, common on phones) or its OUI block isn't in the database yet. A freshly updated vendor database closes the second gap.

How can I tell a randomized MAC from a real one at a glance?

Look at the second hex digit of the address. If it is 2, 6, A, or E, the locally-administered bit is set and the address was generated by the device — there is no manufacturer to look up.