High Sierra is still available for download for a clean install. Its requirements are at least 2 GB of RAM, and 14.3 GB of disk space. Mac OS High Sierra compatibility starts with late 2009 iMacs and Macbooks, and mid to late 2010 Macbook Pros and Macbook Airs. Its features and changes are mainly in the background of this release, so users won’t see an awful lot of differences between Sierra and High Sierra. The Mac OS High Sierra release date was September 25, 2017. There were also quite a few tweaks and fixes that made users want to get the latest Mac OS High Sierra download at the time. Mac OS High Sierra launched with a few new features such as an enhanced Apple Photos with new capabilities and many security updates and fixes.