How to Clean Install Windows (Delete & Reinstall)

A clean install of Windows is the right way to go when all other software troubleshooting you've tried has been unsuccessful and you want to install or reinstall a "clean" copy of Windows back on your computer.

Most of the time, a clean install is the thing you try after one of Windows' automatic repair processes hasn't solved your problem. A clean install will return your computer to pretty much the same state it was in the day you first turned it on.

In case it's not clear yet: a clean install should be reserved for the most serious of Windows operating system problems since all the data on your primary hard drive partition (usually the C drive) is erased during the process.

Illustration of a person clean installing Windows — Lifewire / Brianna Gilmartin

How to Clean Install Windows

A clean install of Windows is accomplished during the Windows setup process by removing the existing Windows installation (assuming there is one) before installing a new operating system or reinstalling the existing one.

In Windows 10, the Reset This PC process is an easier-to-do, and equally effective, way to clean reinstall Windows. See How to Reset Your PC in Windows 10 for a walkthrough.

In versions of Windows prior to Windows 10, the individual steps involved in completing a clean install can differ greatly based on the operating system you happen to be using:

Important Reminders

Remember, a clean install of Windows will erase everything from the drive that Windows is installed on. When we say everything, we mean everything. You'll need to back up anything you want to save before you begin this process! You can back up your files online or use an offline backup tool.

In addition to backing up the individual files you want to keep, you should also prepare to reinstall your programs. Gather the original installation discs and downloaded program setups to any program you want to put back on your computer. One easy way to document all your installed programs is with the Save to text file option in CCleaner, accessible via Tools > Uninstall.

CCleaner list of programs — Software List in CCleaner.

No program outside of those that come bundled with an original Windows setup will be on your computer after the clean install is complete.

If you only have a restore disc from your computer manufacturer but not an original Windows Setup disc or download, a clean install as described in the linked guides above may not be possible. Your restore disc might instead have a relatively similar process that will restore your entire PC, Windows, and programs, back to the factory default.

Please reference the documentation that came with your computer, or contact your computer manufacturer directly for directions.

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