Before downloading, ensure your hardware is compatible with version 10.12: Late 2009 or newer MacBook Air/Pro: 2010 or newer iMac: Late 2009 or newer Mac mini/Pro: 2010 or newer Memory: Minimum 2GB RAM (4GB recommended) Storage: At least 8.8GB of available space How to Download macOS Sierra 10.12 DMG
The app should be approximately . If it is smaller, the download was corrupted.
Step 4 — Install macOS Sierra
file. You must "install" this package to place the actual macOS installer into your Applications folder: Apple Support Double-click the InstallOS.dmg file to mount it. Open the mounted disk image and double-click the InstallOS.pkg file inside. Follow the onscreen prompts. This install the OS yet; it merely places an app named Install macOS Sierra Applications Apple Support 3. Install macOS Sierra Depending on your needs, choose one of these two methods: Method A: Direct Upgrade (Easiest)