How To Reinstall a Mac

Authored by: Support.com Tech Pro Team

1. Introduction

Reinstalling could come up naturally in the course of usage of a Mac. What does this mean? It means to get rid of the current OS on the mac with all the files left on it (after creating a backup of important files of course).

There are several reasons while one may attempt to reinstall a Mac. One common reason is erratic operation of the Mac's OS. Some rightfully believe that reinstalling such Mac could easily fix the issue.

In other cases you might simply be planning on selling the Mac or giving it away and you would not want the buyer to have access to your files so you reinstall. Also, you might not like the version of OS your Mac is running currently and you want it to run the one it was shipped with, you reinstall.

In this guide we'll be going through the steps you should take when you want to reinstall your Mac.

2. Backing Up Your Files In Preparation Before Reinstalling Your Mac

Just as was mentioned in the introduction above, the first step to follow before attempting to reinstall your Mac is to create a backup of your important files, this is very vital as you might lose those files in the course of reinstalling your Mac

Time Machine is the built in backup tool for Mac. To ensure the safety of your files and because backups eat a lot of space, it is recommended to use a dedicated external drive to store them. External drives compatible for use as backup drives are:

External drives that are connected to your Mac via a FireWire drive, Thunderbolt or a USB.
External drives that are connected to an AirPort Extreme Base Station (802.11ac model) or AirPort Time Capsule.
AirPort Time Capsule.
Another Mac shared as a Time Machine backup destination.
Network-attached storage (NAS) device that supports Time Machine over Server Message Block (SMB).

To access the Time Machine;

Click the Apple Icon on the top left corner of your screen to open the drop down Apple menu.
Click System Preferences.

Then click Time Machine from the array of tools displayed on the window.

Connect the external drive you want to create a backup on to your mac.
Tick Encrypt Backup Disk to safeguard your backup.

Click Use as Backup Disk.
Click Select Backup Disk on your time machine dashboard.

Select your backup disk from the list of available drives.
Tick the Encrypt Backup.

Click Use Disk to initiate the backup process.

Once the backup is complete you'll get a prompt informing you of it, you can now proceed to the next step.

3. Prep Your Mac For Reinstalling

Click on the Apple icon on the top-left part your home screen.
Click the Restart button on the ensuing drop-down menu.

Restart the Mac when the prompt appears.
Restart your computer in Recovery Mode by simultaneously pressing and holding the âŒ˜ Command button as well as the R button, immediately after you've clicked the Restart button. A successful key combination takes you to the Mac OS Utilities window.

4. Format Your Mac's Drive

Click on Disk Utility.
Select Continue.

Pick your Mac's hard-drive on which your Mac OS is installed from the options on the left side of the screen, (this is your startup disk) then choose Edit and then Delete APFS Volume from the menu bar

Go to the tabs at the top of the screen and click Erase. A pop-up page appears.

Click on Format. A drop-down menu will open up.

Click on the APFS or the Mac OS Extended option from the drop-down menu.

Select Erase located in the bottom-right part of the window.

Exercise some patience while your Mac's hard-drive finishes erasing after a while. Ensure to keep it plugged in and charging in order not to disrupt the process.

5. Reinstall Your Mac

Select Done when the process is over. This completes the OS erasing process.
Again, head over to Disk Utility.
Select Quit Disk Utility from the options available to return to the Recovery page.
Click on Reinstall macOS, then select Continue. The OS will reinstall itself to your computer.
Setup your Mac by following the on-screen prompts.