How to find the 12 digit Mac Address
Both your MacBook's wireless and Ethernet network interfaces have 12-digit MAC addresses that help identify the computer's networking hardware on your network. These addresses can be handy for network troubleshooting or when you install new hardware such as a router. You can view the MAC addresses in your MacBook's network settings, with your Ethernet address listed as a MAC address and your wireless address identified as a Wi-Fi address.
1. Click the Apple menu, and then select "System Preferences."
2. Click the "Network" icon in the "Internet & Wireless" group of options.
3. Select the "Wi-Fi" to find the MAC address for your machine's wireless interface. Click "Advanced" to see your MAC address at the bottom beside "Wi-Fi Address." Click "OK" to leave the Wi-Fi settings.
4. Select the "Ethernet" or "USB Ethernet" option to find your device's MAC address for its wired interface. Click "Advanced," and then select the "Hardware" tab to see your device's Ethernet MAC address listed as the first item beside "MAC Address." Click "OK" to exit the Ethernet settings.