Install OS X El Capitan.app. From the link above you download Install MacOSX.dmg, on opening that you will see Install MacOSX.pkg, double-clicking on that will open an installation dialogue, this will then convert InstallMacOSX.pkg. To the Install OS X El Capitan.app which will be in your Applications folder. Mac Os X Mountain Lion Upgrade To El Capitan Os If you're using macOS Mojave or later, get macOS Big Sur via Software Update: choose Apple menu System Preferences, then click Software Update. Or use this link to open the macOS Big Sur page on the App Store: get macOS Big Sur.

macOS Big Sur elevates the most advanced desktop operating system in the world to a new level of power and beauty. Experience Mac to the fullest with a refined new design. Enjoy the biggest Safari update ever. Discover new features for Maps and Messages. And get even more transparency around your privacy.

Check compatibility

macOS Big Sur is compatible with the following computers. If your Mac isn't compatible, you might be able to install an old version of macOS instead.

MacBook introduced in 2015 or later
MacBook Air introduced in 2013 or later
MacBook Pro introduced in late 2013 or later
Mac mini introduced in 2014 or later
iMac introduced in 2014 or later
iMac Pro
Mac Pro introduced in 2013 or later
View the complete list of compatible computers.

If upgrading from macOS Sierra or later, your Mac needs 35.5GB of available storage to upgrade. If upgrading from an earlier release, your Mac needs up to 44.5GB of available storage. To upgrade from OS X Mountain Lion, first upgrade to OS X El Capitan, then upgrade to macOS Big Sur.

Download macOS Big Sur

If you're using macOS Mojave or later, get macOS Big Sur via Software Update: Choose Apple menu  > System Preferences, then click Software Update.

Or use this link to open the macOS Big Sur page on the App Store: Get macOS Big Sur. Then click the Get button or iCloud download icon.

Mac Os Mountain Lion Vs El Capitan

Install macOS Big Sur

Os X 10.8 To El Capitan

After downloading, the installer opens automatically. Click Continue and follow the onscreen instructions.

Please allow installation to complete without putting your Mac to sleep or closing its lid. During installation, it might restart and show a progress bar or blank screen several times. You might find it easiest to begin installation in the evening so that it can complete overnight, if needed.

Stay up to date

Os X Mountain Lion To El Capitan 10

After installing macOS Big Sur, you will be notified when updates to macOS Big Sur are available. To check for updates, choose Apple menu  > System Preferences, then click Software Update.