How to determine Operating System - Apple
Help to determine OS version of an Apple computer
Apple - To find the version of OS X you have installed, use these steps:
- From the Apple menu, choose About This Mac.
2. The version number of OS X you're using appears directly below the words "OS X."
Note: You can also visit What my OS?
. This site will list your operating system at the top of the page. It will also give you directions to manually check OS version on older versions if necessary. website