How To Clean Install Windows 10 From ISO File (Without USB/DVD)

Microsoft has started pushing out Windows 10 for users who have already registered for the free upgrade. Many users who have upgraded their Windows 7/8.1 installations to Windows 10 now want to perform a clean install of Windows 10.
After officially releasing Windows 10, Microsoft has released Windows 10 Media Creation Tool to help users download Windows 10 ISO images from Microsoft servers. The tool is useful for users who would like to clean install Windows 10 after upgrading to Windows 10.
Although the Media Creation Tool allows you create a bootable DVD or USB of Windows 10, many of you might be wondering if it’s possible to clean install Windows 10 right from the ISO image.

Install Windows 10 directly from ISO file

Well, it’s possible to clean install Windows 10 from an ISO file. Clean installing Windows 10 from ISO is not vastly different from clean installing Windows 10 from USB or DVD. The only difference is that we are not going to create bootable media while installing Windows 10 directly from the ISO file.
What about the product key?
Note that you won’t need a product key if you have legally upgraded your current PC from Windows 7/8.1 to Windows 10 and successfully activated it, before clean installing Windows 10 on the same PC.
When you are prompted to enter a product key during the product installation, click Skip button. Your PC will be automatically activated after installing Windows 10 as long as you have installed the same edition of Windows 10 was activated on your current PC by using the free upgrade offer.
However, when you clean installing Windows 10 on a different PC or newly built PC, you will have to enter a valid product key.
WARNING: Many users are reporting on Microsoft support forums that they are unable to activate their Windows 10 installation after the clean install. It looks like many users are having this issue. So, clean installing Windows 10 at this point of time might not be a good idea.

Perform clean install of Windows 10 from ISO image

Here is how to clean install Windows 10 from ISO image file without having to create bootable USB or DVD.
Step 1: If you haven’t downloaded your Windows 10 ISO yet, please follow the instructions in our download Windows 10 ISO from Microsoft guide to download the ISO image file.

Clean install from ISO Windows 10

Step 2: On your Windows 10 PC, where you want to perform clean install of Windows 10, back up all data as we are going to clean install Windows 10 by removing installed programs and personal files. So it’s a good idea to backup everything using a good backup software.
Step 3: Right-click on the Windows 10 ISO image file, and then click Mount option to mount the ISO image.

Clean install Windows 10 from ISO file step1

Step 4: Open up This PC, and then open up the newly mounted drive (containing Windows 10 installation files) by right-clicking on the drive and then clicking Open in new window.

Clean install Windows 10 from ISO file step2

Step 5: Double-click on the Setup.exe file.
Step 6: When you see the following screen, select the first option labelled Download and install updates (recommended), or you can also select the option titled Not right now, as we can always download and install updates after clean installing Windows 10.

Clean install Windows 10 from ISO file step3

If you have selected Download and install updates option, the setup will check for available updates and download them if available.
Step 7: Next is the user agreement screen where you need to click Accept button to accept the license terms to install and use Windows 10.

Clean install Windows 10 from ISO file step4

Step 8: Once again, the setup might start looking for updates and download them.
Step 9: Once everything is ready, you will see Ready to install screen.
Step 10: Here, select Keep nothing if you want to perform a clean install of Windows 10 by removing all installed programs and data. We have selected Keep personal files and apps as we don’t want to lose installed apps and important data.

Clean install Windows 10 from ISO file step5

And if you want to keep you data, please select Keep personal files option by clicking Change what to keep link.
Step 11: Finally, click Install button to begin installing Windows 10.
Note that although the installation screen shows “Upgrading” message, it’s actually clean installing.