Get Sierra from the App Store. Click the Download button on the Sierra page. If your Mac is compatible with Sierra, a file named Install macOS Sierra downloads to your Applications folder. After download is complete, the installer opens automatically. Click Continue and follow the onscreen instructions. Read 'Mac OS X Snow Leopard: The Missing Manual The Missing Manual' by David Pogue available from Rakuten Kobo. Sign up today and get $5 off your first purchase. For a company that promised to "put a pause on new features," Apple sure has been busy-there's barely a featur.
You can upgrade to macOS Sierra from OS X Lion or later on any of the following Mac models. Your Mac also needs at least 2GB of memory and 8.8GB of available storage space.
MacBook introduced in late 2009 or later
MacBook Air introduced in late 2010 or later
MacBook Pro introduced in mid 2010 or later
Mac mini introduced in mid 2010 or later
iMac introduced in late 2009 or later
Mac Pro introduced in mid 2010 or later
To find your Mac model, memory, storage space, and macOS version, choose About This Mac from the Apple () menu. If your Mac isn't compatible with macOS Sierra, the installer will let you know.
Before installing any upgrade, it’s a good idea to back up your Mac. Time Machine makes it simple, and other backup methods are also available. Learn how to back up your Mac.
It takes time to download and install macOS, so make sure that you have a reliable Internet connection. If you're using a Mac notebook computer, plug it into AC power.
For the strongest security and latest features, find out whether you can upgrade to macOS Mojave, the latest version of the Mac operating system.
If you still need macOS Sierra, use this App Store link: Get macOS Sierra. To download it, your Mac must be using macOS High Sierra or earlier.
After downloading, the installer opens automatically.
Click Continue and follow the onscreen instructions. You might find it easiest to begin installation in the evening so that it can complete overnight, if needed.
Please allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart, show a progress bar, or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.