Summary
The easiest way to find your serial number depends on your situation. If your Mac turns on, you can find the serial number right in the interface. If it doesn’t turn on, you’ll need to locate it on the case or original packaging.
Body
If your Mac is working properly, finding the serial number and other info about your Mac is easy. Just click the Apple menu icon at the top of the screen and select About This Mac. You’ll see the serial number displayed along with your Mac’s model number, hardware specifications, and the version of macOS you have installed.
Your Mac’s serial number is printed somewhere on the Mac itself, so you’ll be able to find it if you can’t turn your Mac on. Flip over a MacBook and you’ll see the serial number printed on the Mac itself, near the “Designed by Apple in California” text. On a Mac Mini, you’ll find the serial number on the bottom. On the Mac Pro, you’ll find it on the back panel.