A MAC address is 48 bits long, written as six pairs of hexadecimal numbers separated by colons

A MAC address (Media Access Control address) is a unique identifier assigned to every device that connects to a network — your laptop, phone, printer, smart TV, anything with a network card. It looks like this: 00:1A:2B:3C:4D:5E. Those six pairs of numbers are what make up the full 48-bit length.

The first three pairs (00:1A:2B in the example above) identify the manufacturer — the company that made the network card. The last three pairs (3C:4D:5E) are the unique serial number for that specific device. This two-part structure means billions of devices can each have their own MAC address without duplication.

MAC addresses work only on local networks — the network inside your home, office, or coffee shop. They do not travel across the internet the way IP addresses do. Your router uses MAC addresses to figure out which physical device to send data to when multiple devices are connected.

Key Takeaways

  • A MAC address is always 48 bits long and consists of six pairs of hexadecimal numbers separated by colons, like 00:1A:2B:3C:4D:5E.
  • The first three pairs identify the manufacturer of the network card, and the last three pairs are unique to that specific device.
  • MAC addresses only work on local networks and are used by routers to direct data to the correct physical device.
  • You can find your device's MAC address in network settings on Windows, Mac, or Linux, or in your router's connected devices list.

How the 48-bit structure breaks down

The 48 bits are divided into two 24-bit halves. The first half is called the Organizationally Unique Identifier (OUI), and it tells you who manufactured the network card. Apple's OUI is different from Dell's, which is different from Samsung's. When you see a MAC address starting with 00:1A:2B, that first part is registered to a specific company.

The second half is the device identifier, and it is unique within that manufacturer's range. This is how two Apple devices can both have MAC addresses starting with the same manufacturer code but still be completely different from each other. The manufacturer assigns these numbers sequentially as they produce network cards.

Hexadecimal notation (the 0–9 and A–F characters) is used because it compresses the information. Writing out 48 bits in binary would give you a string of 48 ones and zeros, which is hard to read and type. Hexadecimal lets you represent the same information in just 12 characters.

Where to find your MAC address on different devices

On Windows, open Command Prompt and type ipconfig /all. Look for the line labeled "Physical Address" — that is your MAC address. You can also go to Settings > Network & Internet > WiFi > Advanced, and scroll down to find it listed as "Physical address (MAC)".

On Mac, open System Settings, click Network on the left, select your connection (WiFi or Ethernet), then click Details. The MAC address appears as "Wi-Fi Address" or "Ethernet Address" depending on which connection you are checking.

On Linux, open a terminal and type ip link show or ifconfig. The MAC address is listed next to "link/ether" or "HWaddr". On Android, go to Settings > About Phone > Status, and look for "MAC address" or "Wi-Fi MAC address". On iPhone, go to Settings > General > About and scroll to "Wi-Fi Address".

You can also find every device's MAC address by logging into your router's admin panel. Most routers show a list of connected devices with their MAC addresses, which is useful if you need to identify an unknown device on your network.

Why the length never changes

The 48-bit length is a standard set by the IEEE (Institute of Electrical and Electronics Engineers) back in the 1980s, and every network device made since then follows it. This standardization means any device can communicate with any other device on a local network without confusion about address format.

There is a newer standard called EUI-64 that uses 64 bits instead of 48, but it is not widely used in consumer devices yet. For practical purposes, if you encounter a MAC address, it will be 48 bits long — six pairs of hexadecimal numbers.

The length is also fixed because network hardware is designed to expect exactly 48 bits. Routers, switches, and network cards all have firmware that processes MAC addresses as a fixed 48-bit value. Changing the length would require redesigning all that hardware.

MAC addresses versus IP addresses

People often confuse MAC addresses with IP addresses, but they serve different purposes. A MAC address identifies a device on your local network — it gets your data to the right physical machine in your home or office. An IP address identifies a device on the internet — it gets your data across the world to the right network.

When you send a message to someone across the internet, your device uses the recipient's IP address to route the packet to their network. Once it arrives at their network, their router uses the recipient's MAC address to deliver it to the correct physical device. Both are necessary, and both are always 48 bits and IP addresses are different lengths depending on whether they are IPv4 (32 bits) or IPv6 (128 bits).

Your MAC address does not change when you move to a different network, but your IP address does. If you take your laptop from home to a coffee shop, your MAC address stays the same, but your IP address changes because you are now on a different network.

When you might need to know your MAC address

Network administrators sometimes use MAC addresses to restrict which devices can connect to a network — a practice called MAC filtering. If your router has this feature enabled, only devices whose MAC addresses are on an approved list can join the network. If you are setting up a new device and it will not connect, the administrator might ask for your MAC address to add it to the whitelist.

Some internet service providers use MAC addresses to identify your modem and tie it to your account. If you replace your modem, you may need to register the new MAC address with your ISP so they know the device is authorized to use your connection.

MAC addresses are also used in DHCP (Dynamic Host Configuration Protocol), which is how your router assigns IP addresses to devices. The router remembers which MAC address got which IP address, so your devices tend to get the same IP address each time they connect — even though technically that IP is temporary.

Frequently Asked Questions

Can two devices have the same MAC address?

In theory, no — each manufacturer is assigned a range of MAC addresses, and they are supposed to assign each one only once. In practice, it is extremely rare but possible if a manufacturer makes a mistake or if someone deliberately spoofs a MAC address (changes their device's MAC to match another one). On a normal home or office network, you will never encounter this.

Does my MAC address change when I get a new router?

No. Your MAC address is built into your device's network card and does not change based on which network you connect to. Your router is a separate device with its own MAC address. When you replace your router, your devices keep their original MAC addresses.

Is my MAC address private information?

Your MAC address is visible to anyone on your local network and to your router, but it does not leave your network. It is not sent across the internet, so websites cannot see it. However, someone physically near you could potentially detect your MAC address if they are monitoring network traffic, which is why some devices allow you to randomize your MAC address for privacy.

Why do some devices show a different MAC address than what is listed in settings?

Some devices, especially phones and laptops, use MAC address randomization for privacy. Instead of broadcasting the same MAC address every time they scan for networks, they generate a temporary random one. This prevents tracking based on MAC address. The real MAC address is still in your settings — the randomized one is just what the device shows to networks.

What happens if I change my MAC address?

You can change your MAC address in software on most devices, a process called spoofing. This is useful for testing network configurations or bypassing MAC filtering if you have permission. However, changing it will not affect your internet connection or your IP address — it only changes how your local network identifies the device.