Your Mac address usually stays the same, but it can change when you switch networks or your device restarts

A Mac address (media access control address) is a unique identifier assigned to your network card — the hardware that connects your device to WiFi or ethernet. It looks like six pairs of numbers and letters, such as 00:1A:2B:3C:4D:5E. In most situations, your Mac address does not change. It is burned into your network card when it is manufactured.

However, your Mac address can change in specific circumstances. Some operating systems allow you to set a temporary Mac address that overrides the real one. Some networks force devices to use a different address. And some devices generate a new address each time they connect to protect your privacy. Understanding when and why this happens matters if you are troubleshooting network problems, setting up device filtering on your router, or working with network security.

Key Takeaways

  • Your device has a permanent Mac address assigned at the factory, but your operating system can override it with a temporary one.
  • Windows, macOS, and Linux all have settings to randomize or spoof your Mac address, which changes it until you disable the setting or restart.
  • Many modern devices randomize their Mac address when connecting to new WiFi networks to prevent tracking, then use a different address each time.
  • If you set a static Mac address on your router to control which devices connect, a temporary Mac address on the device will bypass that rule.
  • Restarting your device usually resets any temporary Mac address back to the permanent one, unless randomization is enabled in your settings.

The difference between permanent and temporary Mac addresses

Your network card has a permanent Mac address, also called the burned-in address or BIA. This address is set during manufacturing and stored in the card's firmware. It does not change unless you physically replace the network card. This is the address your router sees when you first connect, and it is the one you would use if you wanted to set up Mac filtering (allowing only certain devices to connect).

A temporary Mac address is one your operating system generates and uses instead of the permanent one. When your device sends network traffic, it appears to come from the temporary address, not the real one. Your router and the network see the temporary address. The permanent address stays hidden. This is useful for privacy — it prevents websites and networks from tracking you across different locations by your Mac address — but it can cause problems if you have set up rules based on the permanent address.

How Windows handles Mac address changes

Windows 10 and later have a built-in setting called randomize Mac address that you can turn on or off. When enabled, Windows generates a new temporary Mac address each time you connect to a WiFi network. This address changes every time you reconnect to that same network, or every time you connect to a different network, depending on your settings.

To check or change this setting, open Settings, go to Network & Internet, then WiFi. Click on Manage Known Networks and select the network you want to adjust. Scroll down to find the option labeled "Randomize Mac address" or "Private Mac address". If it is set to On, Windows is using a temporary address. If it is set to Off, Windows is using your permanent Mac address. Restarting your device does not reset a randomized address — it stays randomized until you turn off the setting.

How macOS and iOS handle Mac address changes

Apple devices use a feature called Private WiFi Address on macOS, iOS, and iPadOS. When you connect to a WiFi network, your device generates a temporary Mac address unique to that network. The next time you connect to the same network, it uses the same temporary address. But when you connect to a different network, it generates a new temporary address for that network.

This is different from Windows randomization — Apple ties the temporary address to the specific network, not to the connection event. You cannot easily turn off Private WiFi Address on most Apple devices, though you can disable it for individual networks. On macOS, go to System Settings, click WiFi, select the network, and look for an option to use your permanent address. On iPhone or iPad, go to Settings, WiFi, tap the information icon next to the network name, and toggle off "Private Address".

How Linux handles Mac address changes

Linux does not randomize Mac addresses by default, but most Linux distributions include tools to do it manually. The most common tool is macchanger, which you can install through your package manager. Once installed, you can set a random Mac address, a specific Mac address, or reset to the permanent one.

To use macchanger, you typically need to disconnect from the network first, then run a command to change the address, then reconnect. The address stays changed until you change it again or restart your device — restarting usually resets it to the permanent address unless you have set up a script to randomize it on startup. Some Linux desktop environments also include graphical tools to manage this, but the command line is the most reliable method.

When your Mac address changes without your action

Some networks force devices to use a different Mac address than the one they report. This happens on certain corporate networks and some public WiFi systems that use Mac address translation or network address translation (NAT). From your device's perspective, nothing has changed — your operating system still reports the same address. But the network sees a different one. This is usually invisible to you and does not cause problems unless you are trying to troubleshoot network connectivity.

Guest networks on some routers also assign temporary Mac addresses to devices. When you connect to a guest network, the router may give your device a temporary address that is different from the one it uses on the main network. This prevents guest devices from being tracked across networks and adds a layer of security. Once you disconnect from the guest network, your device returns to using its normal address on the main network.

What happens when Mac address changes break your setup

If you have set up Mac filtering on your router — a whitelist or blacklist of devices based on their Mac address — a randomized or temporary Mac address can break that rule. Your device will appear to be a new device each time it connects, and the router will not recognize it. If you have a whitelist (only these devices can connect), your device will be blocked. If you have a blacklist (these devices cannot connect), your device will be allowed through.

To fix this, you have two options. First, you can disable Mac address randomization on the device itself. Second, you can disable Mac filtering on your router and use a different security method, such as a strong WiFi password or WPA3 encryption. If you need to keep Mac filtering for security reasons, disable randomization on the devices you want to allow, and note their permanent Mac addresses.

Another common problem is DHCP reservation — assigning a static IP address to a device based on its Mac address. If your device is using a temporary Mac address, the router will not recognize it and will not assign the reserved IP. The device will get a different IP each time it connects. To fix this, either disable randomization on that device or update your DHCP reservation to use the temporary address (though this is less reliable, since the address may change).

How to find your permanent Mac address

To see your permanent Mac address, you need to check your network card's firmware, not your operating system settings. On Windows, open Command Prompt and type ipconfig /all. Look for "Physical Address" — this is your permanent Mac address. On macOS, open Terminal and type ifconfig. Look for "ether" — this is your permanent Mac address. On Linux, open Terminal and type ip link show or ifconfig. Look for "link/ether" — this is your permanent Mac address.

If you see a different address in your network settings than the one shown in these commands, your operating system is using a temporary address. To see what temporary address you are currently using, check your router's connected devices list — the router always sees the address your device is actually using, whether it is permanent or temporary.

Frequently Asked Questions

Can I change my Mac address permanently?

No, not in a way that persists. You can change it in software, but the change only lasts until you restart your device or disable the setting. The permanent address is stored in your network card's firmware and cannot be overwritten without specialized tools that most users do not have access to. For practical purposes, treat your Mac address as fixed.

Will changing my Mac address make me anonymous online?

Changing your Mac address only hides your identity from devices on your local network — your router, other devices on the same WiFi, and the network itself. It does not hide your identity from websites or internet services. Your IP address, which is separate from your Mac address, is what websites see. To be anonymous online, you need a VPN or Tor, not a Mac address change.

Why does my device show a different Mac address after I restart it?

If you have enabled Mac address randomization in your operating system settings, your device generates a new temporary address each time it connects to a network. Restarting does not reset it — the randomization setting stays on. To go back to your permanent address, you need to disable the randomization setting in your network settings, then reconnect to the network.

Does my router need to know my real Mac address?

Only if you have set up Mac filtering or DHCP reservation. If you are just connecting to a network normally, your router works fine with a temporary Mac address. The router communicates with whatever address your device is using at that moment. Mac filtering and reservations are optional security and convenience features — most home networks do not use them.

Can I tell if my device is using a temporary Mac address right now?

Yes. Check your router's list of connected devices — it shows the address your device is currently using. Then check your device's network settings or run the commands listed above to see your permanent address. If they are different, you are using a temporary address. If they match, you are using your permanent address.