macOS Sierra is a fantastic update arriving from Apple to make u.s.a. love our Macs fifty-fifty more. It has plenty of new features, and besides has the same like shooting fish in a barrel make clean install and upgrade menstruum every bit did the previous OS.

LEARN More: How to Clean Install the macOS High Sierra?

Note, that getting an upgrade is the easiest mode of installing the new macOS. It saves all your personal files, apps and user data, while a then-called make clean install of Sierra volition erase all information on the startup bulldoze and replace it with a clean re-create of Bone. But, if you like an thought of giving your Mac a fresh kickoff with a new macOS and nothing else, a clean install is the right option for you.

Also, in case y'all've noticed that with time your Mac is running slower, it has unusual startup or shutdown bug and crashes, a clean install may exist a proficient way to get back the speed and fix the problem.

First of all, make sure that your Mac is able to run MacOS Sierra.

Then, y'all should prepare your Mac for the installation:

  • Download macOS Sierra Installer from the Mac App Store. One time the download completes, it will automatically launch. Quit macOS Sierra Installer app without performing the installation.
  • Take a 16GB or larger USB flash drive to create a bootable Sierra installer. This flash drive is only needed for a clean install on your Mac'due south startup drive. Just if you plan to clean install on a non-startup drive (yous have and extra HDD or SSD on your Mac), y'all don't need the USB.
  • Backup your Mac to ensure your personal data is intact.
Download macOS Sierra from Mac App Store

Clean Install macOS Sierra on Your Mac's Startup Drive

If you're going to perform a make clean install on the startup drive, you demand to backup your data, create a bootable copy of the installer, and, finally, kick from the bootable installer. So, let usa begin.

Pace 1: Clean upwards your Mac

To brand sure Sierra has no troubles installing and works fine subsequently, y'all demand to go rid of system junk on your Mac first. Yous could make clean information technology up manually, only using a cleaning app like CleanMyMac X will save you hours on that. Junk removal with CleanMyMac takes only a few minutes. Download CleanMyMac for costless, launch information technology, click Scan, and then Clean. Now you've got plenty of free space and your Mac is costless from system trash.

Stride 2: Back upward your data

Note: A make clean install of macOS Sierra on the startup drive completely erases all data on that drive: all your files and documents, including music, movies, pictures, and even apps.

Then, If you lot skip this step, you wouldn't be able to recover your data if something goes wrong.

To fill-in your Mac:

  • Open up Fourth dimension Machine.
  • Click Select Disk.
  • Choose where you wish to save your files (to the external bulldoze or to the cloud storage).
  • Click On to turn Time Machine on.
  • Click on the "pointer clock" icon and select Back Up Now in the menu bar at the top of the screen.
Time Machine Backup

Step 3: Clean Install macOS Sierra on your startup disk

ane. Create a bootable flash drive with macOS Sierra.

Kickoff, make certain your USB flash drive is formatted and named as "Untitled".

  • To format a USB drive launch Disk Utility (Finder -> /Applications/Utilities/Disk Utility).
  • Select your USB drive under External.
  • Click the Erase tab at the top of the Disk Utility window. Select Mac Bone Extended (Journaled) from the format list. Then, click the Erase button. When the procedure is complete, click Done, and close the Disk Utility window.
  • If your drive is named something else, you need to rename information technology (Open Finder -> correct click on the USB drive and choose Rename).

Now, your USB flash drive is ready.

  • Launch Terminal (Finder Applications Utilities Terminal)
  • Enter the following text into Terminal:
    sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction
  • Hit the Enter central.
  • Last will ask you for an admin password (the one y'all use to log in). It won't display characters when you type, then only practise it. Hit Return. You lot'll see that Last erases your drive. Then, Final will re-create the installer file to your disk. This volition accept a few minutes. When the process is complete, the Final window volition written report "Done." You can quit Terminal and your bootable macOS Sierra installer USB bulldoze is ready for use.

As well, you can follow the instructions from an Apple article on how to create bootable installer.

two. Plug in the bootable macOS Sierra installer USB drive to your Mac.
3. Restart your Mac while holding the Pick key or Cmd+R. Make sure to continue it pressed!
iv. When Mac restarts, you'll run into the macOS Startup Director with a listing of bootable devices that your Mac can starting time up from.
v. Employ the arrow keys to choose your USB bulldoze with macOS Sierra installer. Press Enter.
half dozen. Select Disk Utility.
7. In the window, at the top of the left bar, select your Mac'south Main Drive (it looks like a MacintoshHD).
8. Select the Erase tab located next to the Commencement Assist push button at the pinnacle.
9. About the eye of the window, select the Format drop-downwards list and select Mac OS X Extended (Journaled) type.
10. Click Erase (Note: this will erase all your information from your principal bulldoze!) and give the drive some time to format.
11. When it's done, close Disk Utility and select "Install macOS" from the carte.
12. Select your main drive and install the new macOS Sierra 10.12.

Follow these Sierra install instructions and savor your newly clean-installed macOS Sierra.

Clean Install on a Not-Startup Drive

This type of clean install doesn't require you to brand a bootable copy of the macOS installer, since you tin run the installer straight from your Mac's startup drive. Merely y'all demand to have another hard drive or book that you can use for installing macOS.

Then, this is the easiest way to clean install macOS 10.12. Simply use an extra drive or volume (it doesn't take to necessarily be empty already, you just need to be fine with it being erased) and install Sierra there.

Step 1: Erase your non-startup drive

If your non-startup drive has any other Mac Os, erase it before installing Sierra. If the target drive only has personal data on it, or is already empty, y'all can skip the erase process.

To erase the non-startup drive, employ a Mac'south Bulldoze Using Disk Utility (OS X El Capitan or later)

After the non-startup bulldoze is erased, yous tin starting time the install process.

Step 2: Download the macOS Sierra Installer from the Mac App Store

When the macOS download completes, information technology will automatically launch the installer. Quit the macOS Sierra Installer app without performing the installation. You'll find the macOS Sierra Installer in the /Applications folder.

Step iii: Outset the Installation of macOS Sierra on the Not-startup drive

  • Launch the Installer from /Applications folder.
  • Click Go along.
  • Bank check the not-startup drive that you tin can install Sierra on (commonly, the installer will brandish the default target for the installation of macOS Sierra as the startup bulldoze (Macintosh Hard disk). So, you should to click the Bear witness All Disks button, and the installer will brandish a list of all fastened volumes).
  • Click the Install button.
  • The macOS Sierra installer volition display a progress bar. You'll be guided through the macOS Sierra setup process to create a user account, set up date and time, and other introductory stuff.

Enjoy your fresh, make clean-installed macOS Sierra.