How To Erase Your Mac’s Hard Drive and Reinstall OS X

If you sell your Mac or just want a fresh start, you can erase the drive and reinstall OS X. Here’s how to do it with a Mac Mini running Mountain Lion.

I’ve been getting rid of my Apple products lately and selling them on eBay. So, I thought I would remind everyone that you need to erase your data and reinstall OS on your computers and devices before selling it off.

Note: I started by selling my iPad 3, and if you’re selling yours, check out my article on how to erase your data and reset it.

Erase the Hard Drive

Start your Mac and hold down the Command + R key combination. That brings up OS X Utilities. Select Disk Utility and click Continue.

Disk Utility

Select the local drive and click the Erase tab, Format should be set to Mac OS Extended (journaled), the click the Erase button. That will erase all data and reformat the hard disk.


If you want to be extra secure, select Security Options, then select 7-Pass Erase, which meets the US Department of Defense 5220-22 M standard. This does a similar job of securely erasing your drive as DBAN for Windows.

Reinstall Apple OS X Mountain Lion

After that’s done, go back to OS X Utilities and this time highlight Reinstall OS X and click Continue.

OS X Utilities

Next you’ll get the OS X Mountain Lion screen. Click Continue at the bottom, and on the message that comes up, click the Continue button.

OS X Mountain Lion

Now agree to the terms of service for the software license.

EULA Agree

After that select the hard drive you want to install OS X on. If you only have one drive, it will be selected for you automatically.

Select HD Install

Before OS X installs, you’ll need to log in to your Apple Account.

Apple Account

Now you can kick back and wait while OS X reinstalls.


You’re Mac will restart a few times automatically while everything is erased and reinstalled. It can take a while, might want to play some Angry Birds for a while or grab a beer!

Continuous Install

After the reinstall, you or the new owner will need to go through the setup process, transfer files, connect to WiFi…etc. After that, you’ll be able to rock the new freshly installed OS X.

OS X Mountain Lion Desktop

1 Comment

1 Comment

  1. Tony

    February 26, 2013 at 7:36 pm

    Recently did this before selling my wife’s MacBook Pro. It still shows up in the list of devices on her iPad’s find my iPhone app. It also shows the ability to wipe the device. I doubt the new owner would appreciate that however funny it would be.

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