How to Perform a Clean Install of OS X Yosemite

OS X Yosemite is officially out and available to the public. It’s the latest version of OS X from Apple, and it comes with a whole new look and a host of new features, including Handoff (which lets you go back and forth on your iPhone or iPad with certain tasks).

OS X Yosemite now available on the Mac App Store free.

While most users are happy with the easy upgrade process that OS X has, some users prefer to start from scratch with a clean OS install when upgrading to a completely new version. A fresh clean install means that your computer’s hard drive is completely wiped and OS X Yosemite is restored to factory settings. This means that no applications are installed and no files are stored; default apps and files that only ship with OS X Yosemite.

Personally, I always do a clean install. There are just too many issues that can arise when upgrading, and I have so many files that they can get erratic and cause unnecessary slowdowns after upgrading. Basically, when you do a simple upgrade, the new OS is installed and then the installer takes all the old files and dumps them over the newly installed OS, which can easily cause problems.

That said, here’s how you can install a fresh copy of OS X Yosemite and start with a clean slate.

Be careful though: Performing a clean install of OS X requires you to make a bootable installation drive using a USB flash drive. You’ll be navigating a bunch of files and dealing with Terminal. If this isn’t something you enjoy doing on your own, we recommend simply upgrading or talking to a friend who can help you perform a clean install.


First, you’ll want to make sure OS X Yosemite is supported by your Mac. Some Macs dating back to 2007 support OS X Yosemite, but for a complete list of supported Mac models, check out this list.

You’ll also want to back up everything before starting the clean install. You can use Time Machine to easily back up all your files to an external hard drive, or you can manually pick and choose the files you want to keep and then export them to an external hard drive or USB flash drive.

Next, download OS X Yosemite from the Mac App Store. It will automatically download and save to the folder. Also, it can automatically start the installation process after it finishes downloading. If this happens, cancel immediately.

Making a Bootable USB Drive

To install a clean fresh copy of OS X Yosemite, you must create a bootable installation drive using a DVD, USB flash drive, or external hard drive. We’ll be using a USB flash drive for this tutorial, because not everyone’s Mac has an optical drive, and you most likely already have a USB flash drive. Make sure it is at least 8GB in size.

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  1. Plug in your USB drive and turn it on.
  2. Select the USB drive in the sidebar and click the tab.
  3. Select the box and name it (it should already be named like this).
  4. Click it and wait for the format to finish.
  5. Once complete, close Disk Utility and save the . Type the following command and press Enter:

sudo /Applications/Install\ OS\ X\ --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ --nointeraction

This command will officially create the USB boot drive and will take about 20 minutes to complete, export or import. Don’t mess with the Terminal or remove the flash drive while it’s doing its job. Once done, it will say.

Installing OS X Yosemite

Now that you have a bootable USB stick with OS X Yosemite on it, it’s time to set it up. Restart your Mac with the USB drive inserted and hold down Option/Alt. This will open a menu where you will select an installation driver. Select the USB drive you just made (in this case it will usually be called and will be orange). Click the up arrow under the drive icon to get started.


Now, before installing OS X Yosemite, you will want to erase and reformat your hard drive, so go to the top menu bar on the screen and click it.


From there, follow these steps:


This is a rather complicated way to create a bootable installation drive, but we anticipate that when OS X Yosemite is released a few months later, some third-party tools may be released that will speed up the bootable disk creation process a bit. similar to the OS X Mountain Lion tools that easily create a USB installation drive for you. But for now, this seems to be the fastest way that works.

Moyens Staff
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