IP and InternetWhat is a MAC address?
A MAC address is the address of a device's network hardware. It is used only on the local network and never travels across the internet.
What it is
Every Wi-Fi chip, network socket and Bluetooth chip is made with an address of its own, called a MAC address ("media access control"). It is 48 bits long and is written as six pairs of hex digits, for example 3C:5A:B4:1E:9F:02. Windows writes it with dashes and calls it the "physical address".
A phone or laptop has more than one: one for Wi-Fi, one for Bluetooth, and one for each cable port.
How it differs from an IP address
| MAC address | IP address | |
|---|---|---|
| Comes from | The maker of the hardware | The network you join |
| Changes when you move to another network | No (unless randomised) | Yes |
| Used for | Delivery inside one local network | Delivery across networks and the internet |
| Seen by websites | No | Yes (the public one) |
Inside your home, the two work together. Your router knows "the device with this MAC address has been lent this IP address". When data for that IP address arrives, the router uses the MAC address to hand it to the right device over Wi-Fi.
Reading a MAC address
The first three pairs identify the maker of the network chip; makers are given blocks of numbers by a standards body, the IEEE. The last three pairs are a serial number chosen by the maker. That is why a router can often show a brand name beside each connected device. The name is the maker of the chip, which may not be the brand on the box.
Where to find it
- Windows: Command Prompt,
ipconfig /all, the line "Physical Address". - Android: Settings › About phone (Status on some phones), "Wi-Fi MAC address"; or in the details of the connected Wi-Fi network.
- iPhone: Settings › General › About, "Wi-Fi Address"; the address used on one network is in Settings › Wi-Fi › (i).
- Mac: System Settings › Network › Wi-Fi › Details › Hardware.
- Linux:
ip link, the value afterlink/ether. - Printers, televisions and other devices: on a sticker, or in the network section of the settings menu.
Random MAC addresses on phones and laptops
Because a fixed MAC address lets shops, malls and public Wi-Fi networks recognise the same phone visit after visit, modern systems now show a made-up address to each Wi-Fi network: iPhone ("Private Wi-Fi Address"), Android 10 and later ("Use randomised MAC"), and Windows ("Random hardware addresses"). The device normally keeps the same made-up address for the same network, so home Wi-Fi keeps working.
This matters in two cases: if your router has a rule tied to a device's MAC address (a reservation, a filter, parental controls), or if a college or office registers devices by MAC address. Then turn the setting off for that one network, in its Wi-Fi details.
Is MAC filtering good security?
Routers can be told to accept only listed MAC addresses. It keeps out casual neighbours, but it is weak protection: a MAC address is sent in the clear over the air, and a determined person can copy an allowed one. A strong Wi-Fi password with WPA2 or WPA3 is the real lock. Use filtering only as a small extra, if at all.
Can someone track me with my MAC address?
Only a network you are near or joined to can see it; websites cannot. Random MAC addresses were introduced to stop this kind of nearby tracking.
Can a MAC address be changed?
The one built in cannot, but most systems can present a different one to the network. That is what the random address setting does.
Do two devices ever have the same MAC address?
They should not, since makers number them. A clash on one network causes strange connection drops, but it is very rare.