macOS Sierra requirements

macOS Sierra works on Macs dating back to 2010, and MacBooks and iMacs to 2009. You need to be running Mac OS X 10.7 or later. You need 8.8GB of available storage.

Back up your Mac before upgrading; go to support. apple.com/en-gb/HT201250 for advice on using Time Machine. Go to the Mac App Store and download the free macOS Sierra upgrade.