

If you are running an older OS, you can look at the hardware requirements for the currently supported versions of macOS to see if your computer is capable of running them: 11 Big Sur.

If you are running macOS 10.11 or newer, you should be able to upgrade to at least macOS 10.15 Catalina.

That being said, there’s one exception you should be aware of: macOS 10.14 had a support for some of the older MacPro models with Metal-cable GPU - these are no longer available in Catalina. So if your device runs on Mojave, it will run on Catalina as well. If you plan to run a lot of older programs that don’t have 64-bit versions, then High Sierra is probably the right choice. That system, up to and including its final release Mac OS 9, was a direct descendant of the operating system Apple had used in its Macintosh computers since. If you’re an iPhone or iPad user, then you may want to consider Mojave for the increased compatibility with iOS. The history of macOS, Apple's current Mac operating system formerly named Mac OS X until 2012 and then OS X until 2016, began with the company's project to replace its 'classic' Mac OS. If you’re a fan of dark mode, then you may well want to upgrade to Mojave.
