Performing a clean install of MacOS Mojave may be desirable to some Mac users. A clean install means erasing all data on a hard drive, and then installing a fresh new installation of MacOS Mojave to that Mac. The idea is that a clean install starts fresh, sort of like how a new Mac comes when you first open the box, with no customization, no third party apps, no user accounts, no user data, preferences, settings, caches, no personal files or data, it’s basically just a new clean installation of MacOS Mojave, and nothing else.
While the vast majority of Mac users should simply prepare for and update to macOS Mojave as usual from a prior MacOS system software release, thereby preserving their apps, customizations, personal files, and all else, this walkthrough is intended for users who want to erase a Mac completely and start over fresh to perform a clean install of macOS Mojave 10.14.
To perform a clean install of MacOS Mojave on a Mac, you’ll need the following:
Remember, a clean install will erase everything on the Mac, including all personal files, photos, movies, apps, any customizations or settings, or anything else. A clean install starts new, with absolutely no personalization or your data on the computer. Thus it becomes critical that you have separately backed up your personal data and anything important to you, as failure to do so will result in permanent data loss.
How to Clean Install MacOS Mojave
Warning: This process will erase everything on the Mac, and then perform a new clean install of macOS Mojave only. No personal files, data, or apps will be preserved or included on the Mac, unless you restore that data separately.
Do not proceed without sufficient backups of your important data and computer.
- Complete a full Time Machine backup before starting this process. It’s recommended to have a Time Machine backup, in addition to any manual file backup of your personal data that you wish to keep. Be certain you have backed up any important files, personal data, pictures, etc – do not skip a full backup
- Connect the bootable macOS Mojave installer drive to the Mac via a USB port
- Reboot the Mac, then immediately start holding the OPTION key on the keyboard
- Hold OPTION key until you see a boot selection menu appear on screen, then choose the “Install macOS Mojave” drive (this is the bootable USB installer) from the choices
- At the “macOS Utilities” screen, select “Disk Utility”
- In Disk Utility, choose “Macintosh HD” (or whatever your Mac hard drive is named that you want to format and clean install Mojave onto), then select the “Erase” button
- Choose “Macintosh HD” as the drive name, then go to “Format” and select “Mac OS Extended (Journaled)” or APFS depending on which file system format you use, then choose “Erase” – WARNING: ALL DATA ON THE MAC WILL BE PERMANENTLY ERASED
- Once the drive has finished erasing and formatting, quit out of Disk Utility
- Back at the ‘macOS Utilities’ screen, now select “Install macOS” from the available options
- At the “Install macOS Mojave” splash screen, choose “Continue” and then select “Macintosh HD” as the destination to install macOS Mojave, and then choose “Install” to begin the clean macOS installation process
- MacOS Mojave will install fresh on the otherwise empty drive and computer, let this process complete, when finished macOS Mojave will boot up as if it were a brand new Mac
When the Mac has finished installing macOS Mojave, the computer boots up into a fresh clean install of macOS Mojave as if it’s a new computer, thus you’ll go through the standard setup process as if it were a new Mac. There are no personal files, no personal data, no apps, nothing on the Mac except for macOS Mojave and what comes with it by default. Thus, it’s a “clean install”.
At this point, you’ll probably want to setup the Mac as new, and then go about manually re-downloading apps, utilities, and other stuff you use to the Mac, as well as manually restoring any of your important personal files and personal data to the computer. Or you can skip all of that and just use the Mac with a clean install of macOS Mojave as if it were a brand new computer, without restoring or copying any data back to it. That’s entirely up to you.
So that’s how you clean install macOS Mojave. If you have any questions, comments, or other methods for performing a fresh install of macOS Mojave, share with us in the comments below.