Go to the Apple Menu and select "About this Mac". If you have a Core Duo processor, you have a 32-bit CPU. Otherwise (Core 2 Duo, Xeon, i3, i5, i7, anything else), you have a 64-bit CPU. Mac OS X is fairly bitness-agnostic, so either should work.
Herein, what is my Mac operating system?
First, click on the Apple icon in the top left corner of your screen. From there, you can click 'About this Mac'. You'll now see a window in the middle of your screen with information about the Mac you're using. As you can see, our Mac is running OS X Yosemite, which is version 10.10.3.
How do I find out the year of my Mac?
For previous versions of OS X:
- Go to the Apple Menu on the Menu Bar and choose About this Mac.
- Your version of OS X will be in grey text under Mac OS X.
- Note the last 4 characters of the Serial Number.
- Go to the Everymac.com Ultimate Mac Lookup.
- Enter the last characters of your serial number.
How do I know the size of my MacBook air?
Choose Apple (?) menu > About This Mac. The window that appears lists your computer's model name—for example, MacBook Air (13-inch, Early 2015)—and serial number. You can then use your serial number to check your service and support options or to find tech specs for your model.