MAC address analyser
Paste a MAC address, or the output of arp -a, to see what each address really is — a network card, a randomised private address, a multicast group or a virtual machine — and every way of writing it.
Runs entirely in your browser — nothing is sent anywhere
Reading the first byte
Two bits of the first byte decide what kind of address it is. The lowest marks a group (multicast) address. The next marks an address set by software rather than a manufacturer. The quick test: if the second character is 2, 6, A or E, software made the address up.
Common findings on a network
- Many “set by software” addresses on Wi-Fi are phones and laptops using private addresses. Normal, and a reason not to allow devices by MAC address.
- VRRP or HSRP addresses are the gateway your devices use, shared by two routers so either can take over.
- 01:00:5e and 33:33 addresses are multicast: discovery protocols, streaming and IPv6 neighbour discovery.
The IPv6 calculator does the reverse of the EUI-64 row: it spots a MAC address inside an IPv6 address.
Why can’t I find the manufacturer of my phone’s address?
Because it is not the phone’s real address. iOS, Android, Windows and macOS use a random address for each Wi-Fi network by default, so networks cannot track the device. You can see the real one in the device’s settings, or turn off the private address for your own network.
What do the two halves mean?
The first three bytes are the organisationally unique identifier the IEEE assigned to the manufacturer; the last three are the serial the manufacturer chose. Two bits in the very first byte say whether the address is for a group and whether software set it.
Where do I get arp output?
arp -a on Windows and macOS, or ip neigh on Linux, lists the devices your computer has recently talked to on the local network. The [local checks page](/tools/local-checks) explains both.
Can a website see my MAC address?
No. A MAC address only travels as far as the next router, which replaces it with its own. Nothing on the internet ever sees it — which is also why this tool can only read addresses you paste.
Why doesn’t MyIPKit show the manufacturer directly?
The IEEE publishes its registry for lookup but has not clearly licensed copies of it, so rather than ship one, this page sends you to the IEEE’s own search.