macOS Sierra will be available as a free software update for compatible MacBook, MacBook Air, MacBook Pro, iMac, Mac mini, and Mac Pro models in the fall. Many 2007 to 2009 Macs that are compatible with OS X El Capitan will not be upgradeable to macOS Sierra, as the cutoff is now at least Late 2009.
The official list of Macs compatible with macOS Sierra:
- MacBook Air
- MacBook Pro
- Mac mini
- Mac Pro
Apple has shared the full video of its WWDC 2016 keynote, where it also introduced iOS 10 alongside new versions of watchOS and tvOS.