MAC address lookup & formatter
Validate a MAC address, normalise it to every common format, decode its OUI vendor prefix and read the addressing bits. Vendor name is fetched from a public OUI database when available.
What is a MAC address?
A MAC (Media Access Control) address is a 48-bit hardware identifier burned into every network interface — your Wi-Fi card, Ethernet port or Bluetooth radio. Written as six hex pairs (e.g. 3C:5A:B4:1F:2E:9D), it identifies a device on the local network. Unlike an IP address it doesn't route across the internet; it only matters within a single network segment.
OUI: the vendor half
The first three bytes are the Organisationally Unique Identifier (OUI), assigned by the IEEE to the hardware manufacturer. Look it up and you learn who made the network chip — Apple, Intel, Cisco, Samsung and so on. The last three bytes are the device-specific serial portion.
The two special bits
- U/L bit — tells you whether the address is the universal factory-assigned one or has been locally administered (e.g. spoofed or randomised).
- I/G bit — marks the address as unicast (one device) or multicast (a group).
MAC randomisation & privacy
To stop venues tracking you by MAC as you move between Wi-Fi networks, phones now use randomised MAC addresses per network. You'll spot these because the locally-administered bit is set. It's a meaningful privacy win — related to the broader mobile tracking story.
Frequently Asked Questions
Can I find a device's location from its MAC address?
No. MAC addresses aren't routable and never leave the local network, so they carry no geographic information. Location tracking via MAC only works when you're physically near the scanning Wi-Fi equipment.
Why does the vendor sometimes show as unknown or random?
Modern phones randomise their MAC for privacy, producing a locally-administered address with no registered vendor. The tool flags these — an unknown vendor with the “locally administered” bit set usually means randomisation.
How do I change (spoof) my MAC address?
Most operating systems allow it: Windows via the adapter's advanced properties, Linux with ip link set dev eth0 address …, macOS with ifconfig. Spoofing sets the locally-administered bit, which this tool will detect.