Power on the system, or restart it if it’s already on, and immediately press and hold the Option key when it starts booting.

Simply plug your created USB drive into an open USB port on your Mac. There are two different methods to boot your Mac from a bootable USB, depending on which processor your Mac has. You can use Time Machine to easily back up the data on your Mac. This almost always results in a Mac running faster after a clean install, since macOS has started over with a clean slate.īefore you reinstall macOS on your Mac, make sure you’ve backed up all your important data! This is crucial when you do a fresh installation, as it will wipe your hard drive. A clean installation allows you to get rid of junk apps and files that may have accumulated over time. These issues include when your Mac refuses to boot or when you need to recover system files that seem to be lost.Īnother benefit of using a bootable disk for a macOS installation is that you can perform a clean installation. You can also use the built-in recovery tools that come with the macOS installer to troubleshoot and fix different kinds of issues. This can save quite a bit of time, considering the most recent versions of macOS have an installer size of 12GB.

Why Would You Need to Install macOS From a USB?Ĭreating a bootable USB drive and using it to reinstall macOS is a bit of a lengthier process compared to simply updating macOS from the Software Update section of the System Preferences, but it has its benefits.īut creating a bootable USB disk allows you to install or update macOS on multiple systems without having to download the installer on each Mac.

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