A MAC address is a unique hardware identifier assigned to a device's network interface, written as six pairs of hexadecimal digits.
A MAC address (media access control address) is a unique hardware identifier assigned to a device’s network interface, written as six pairs of hexadecimal digits - for example, 00:1A:2B:3C:4D:5E. Like a manufacturer’s serial number, it is set at the factory; unlike the serial, it identifies one specific network interface rather than the whole device, and it is what other equipment on the local network uses to address traffic to it.
Format and example
A MAC address is 48 bits long, conventionally written as six two-digit hexadecimal groups separated by colons or hyphens (00:1A:2B:3C:4D:5E and 00-1A-2B-3C-4D-5E are the same address). The first three pairs are the organisationally unique identifier (OUI), assigned to the manufacturer of the network hardware - so the front half of a MAC tells you who made the chip. The last three pairs identify the individual interface.
A device usually carries several. A typical laptop has separate MAC addresses for its Wi-Fi, Ethernet, and Bluetooth interfaces, and a docking station or USB network adapter brings its own address along with it.
MAC address vs IP address
The two are constantly confused because both “identify a device on a network”, but they sit at different layers. The MAC is physical: fixed to the hardware, meaningful on the local network segment, unchanged when the device moves. The IP address is logical: handed out by whatever network the device joins, and different at the office, at home, and on hotel Wi-Fi. A useful shorthand - the MAC is who the network card is, the IP is where it currently lives.
How to find a MAC address
- Windows - run
ipconfig /alland look for “Physical Address” under the relevant adapter. - macOS - System Settings, then Network, then the details of the active interface.
- Phones and tablets - the About section of the settings lists the Wi-Fi MAC (and note that many devices show a randomised per-network address there too).
- Network kit - printers, access points, and routers usually carry the MAC on a factory sticker next to the serial number.
Why MAC addresses belong in IT asset inventories
The MAC is the bridge between what your network sees and what your register says. When an unknown device appears on the network, its MAC is often the only handle you have - if the register stores hardware MACs, that lookup ends with a name and an owner instead of a shrug. The same field supports DHCP reservations, network access control lists, and confirming that the laptop on the bench is the one the record describes. In AMPthilly, a custom field on the asset record is a natural home for the hardware MAC, sitting alongside the serial number, owner, and history.
The limits of a MAC as an identifier
Treat the MAC as one identifier among several, not the identifier. Modern phones and laptops randomise their Wi-Fi MAC per network by default, so the address a network logs may not be the hardware one. Addresses can be spoofed in software, which rules the MAC out as a security control on its own. And dock-based setups mean the address on the wire belongs to the dock, not the laptop. None of this makes the field useless - it makes the case for pairing it with a physical asset label and your own asset ID, so identification never depends on a single number. For more identifiers worth recording, see the glossary.
Related terms
- Serial Number - the manufacturer’s identifier for the whole device, recorded alongside the MAC
- Asset Label - the physical label carrying your organisation’s own ID
- Asset Marking - durable identification methods for equipment
- QR Code - the scannable format that links hardware to its record
- Barcode - the 1D label format common on factory stickers