How to Clean Install macOS Big Sur/Catalina, Clean Restore using Bootable Pen drive

Last Updated on Nov 12, 2020

The latest version of macOS is currently macOS Big Sur 11/macOS Catalina. Let’s follow this tutorial on install a New Copy of MacOS Big Sur on your MacBook, Mac. “Install MacOS Big Sur from USB” or “Reinstall Mac OS without USB Disk.” This installation process removes internal OS Errors, Speed up Your Mac, Free Up storage from root folders, and more. Some users are using clean install for resell old Mac or prepare your Mac like new.

Note that currently, the only version is available and for registered developers. The remarkable features of macOS Big Sur are New Safari Features, a New Control center, Messages app, and Dark Mode, Stacks, Dynamic Desktop, a new screenshot tool, and much more.

Doesn’t matter what is available in macOS until you won’t download and install it on your Mac. Once you get an installation error, undoubtedly you will be out of the mood. Instead of risking installation, why should we download the macOS and perform a clean install on Mac?

[Also Helpful: Reinstall MacOS without Data Loss. This process can’t erase data, online install Fresh copy of MacOS.]

Benefits of clean installs

There are a lot of advantages when you perform a clean install on your Mac. Like, all the glitches or strange behavior of your Mac because of faulty apps or driver upgrades will be fixed. A clean install can make your Mac more efficient and reliable and also you will get some free space out of junk files.

So before we start clean install should possess a USB thumb drive of 8GB or more. Take a backup of Mac using Time Machine if anything goes wrong you can restore data from the backup.

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Check if your Mac or MacBook is compatible with macOS

The devices which are compatible with macOS are listed below. If you have one of the devices from the list then only try to install macOS on your Mac or MacBook.

Also Check it out macOS Big Sur Supported Macs.

  • iMac 2014 and later
  • MacBook Air 2013 and later
  • iMac Pro 2017 and later (all models)
  • MacBook Pro Late 2013 and later
  • Mac Pro 2013 and later
  • MacBook 2015 and later
  • Mac mini 2014 and later

To check whether your device is eligible for macOS Big Sur to follow the steps,

  • Step 1: Tap on the “Apple” icon and open “About This Mac”.
  • Step 2: Next, click on the “Overview” panel and see the model and year of your Mac or MacBook.


Pre-install Notes: Quickly Note down all the installed app on Mac, That’s Easy to reinstall after clean setup complete.

Skip this if not interested, and Jump to Create Bootable Drive

  1. If in case anything goes wrong it is possible you might lose data or application. So it is advisable to make a note of what data will be transferred to the new macOS. A note can be also helpful in tracking the apps, in case you lost some of them.
  2. Take a screenshot of the “Application” folder. Press “Command + Shift+ 4” and then press Space to capture the Finder tab. If you want to create a document containing a list of applications then yes you can do that also. Take a look. Step 1: Go to the “Application” folder. Step 2: Press “Command+A”, now all the apps will be selected in the Finder. Step 3: Next, press “Command+C”. Step 4: Launch “TextEdit”. Step 5: Create a new document with plain text format and then paste it by “Command+V”. Step 6: Save the document in an external drive or any cloud storage.

NOTE: If your Mac contains any app which isn’t downloaded from the Mac App Store then also make a note of serial number or anything which can be used as an identity.

Finally, de-authorize the services on Mac or MacBook including iTunes ID.

  • Step 1: Launch “iTunes” and select “Account.”
  • Step 2: Open “Authorization” and from their de-authorize the account of iTunes.

Create Bootable Installer

Full Guide: Create Bootable MacOS Mojave USB install Drive. If you have, skip this step and jump to the next step.

Download.Dmg setup file of MacOS Mojave from the App Store and use it to make a bootable drive. Apple Store > Search MacOS > Get or Download.

Step 1: Erase the thumb drive by visiting the “Disk Utility” folder.

  • Step 2: Rename the thumb drive “UNTITLED.”
  • Step 3: You should select the format of the thumb drive as “OS X Extended Journaled” and “Erase” the drive.
  • Step 4: Create a macOS Big Sur Bootable drive, Directly search from the “Spotlight” and open “Terminal”.
  • Step 5: Enter the following code into the terminal,

MacOS Big Sur

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia –volume /Volumes/UNTILTED

MacOS Mojave

sudo /Applications/Install\ macOS\Mojave.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ macOS\ Mojave.app

MacOS Catalina

sudo /Applications/Install\ macOS\ Catalina\ Beta.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –nointeractions –downloadassets

  • Step 7: Hit Enter.
  • Step 8: Enter the required “Administrator Password.”
  • Step 9: Leave it for a few minutes, and your bootable installer will be ready.

Reboot and Clean Install of MacOS Big Sur on Mac, iMac, MacBook Pro, MacBook Air

Now you have a bootable USB drive ready, connect to Mac.

Restart the Mac and press and hold “Option” key from your Keyboard, when Mac makes a rebooting sound or haptic feedback.

1 Clean Install MacOS Mojave

1: See the “MacOS Installer Drive” screen,

2. Click on “Install macOS Big Sur” from the drive list.

3. Now, you are on the macOS utility screen. Select “Disk Utility” and click on “Continue.”

2 Disk Utility for Clean install MacOS Mojave

4. Erase Drive that installed previous or Corrupted MacOS for Clean install.

3 Erase Data from Drive to clean install MacOS Mojave

Select Drive from the Right pane, Tap on Erase from the Top tabs.

Choose the APFS Formate File system (Available this formate only on SSD Equipped Mac) or Extended Journaled.

Once you complete, Tap on “Done.”

4 Complate Erase Process on Mac

After the Process completed, you can see Drive is Erased and free space to install the new MacOS. Now “Close window,” To see back on Disk utility window.

5. From the Disk Utility window, click on “Install MacOS.”

Click to continue to start the installation of macOS Mojave.

In the process of installation, Select your “Erased Drive (Macintosh HD)” and “Install.”

_Macintosh HD

Your Welcome screen jumps to dark mode.

Method 2: if you have Time machine Backup that can choose “Restore from Time machine Backup,” this option will copy all old data after a clean install.

Now restore your data and files from Time Machine backup or also you can restore manually and arrange them the way you like.

Don’t miss to like and share my article for Clean install MacOS Big Sur on Mac – Clean install macOS Big Sur on Mac (With Picture guide).

Jaysukh Patel is the founder of howtoisolve. Also self Professional Developer, Techno lover mainly for iPhone, iPad, iPod Touch and iOS, Jaysukh is one of responsible person in his family. Contact On: [email protected] [OR] [email protected]

2 Comments
  1. Will restoring from Time Machine also restore all of the little ‘cache’ and ‘temporary files’ from the previous backup?

    If so I would install everything manually.

    • if you are irritating with Slow speed issues and Bug. Don’t do that try to install manually.

      Restore will copy all the data (Files and Folders) as like earlier.

      I am using Clean installed macOS Mojave. Very happy to use my mac.

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