How to: Perform a Clean Install or Reinstall of Windows 10

Please be sure to follow me on Twitter @adacosta for the latest tips, tricks and updates in the world of Windows 10. -

Technical Level : Intermediate

If you have installed a recent release of Windows in the past 5 years, you pretty much know what it will be like to install Windows 10. In this article, we take a look at performing a clean install. This includes starting a clean install from within a running version of Windows or a hard disk/SSD with no previous Windows installations.


  • Perform a clean install by booting from install media (DVD or USB thumb drive)
  • Perform a clean install using Reset in Windows 10 or Windows 10 Refresh Tools (Start Fresh)
  • Perform a clean install from within a running version of Windows 7, Windows 8/8.1 or Windows 10

Previously, Windows 7, Windows 8.0 and Windows 8.1 users needed to have either of those versions of Windows installed and activated in order to qualify for the free upgrade offer. For users who needed to perform a clean install of Windows 10 from the outset, it was a two step process of first validating the machine through the upgrade routine, ensure the Windows 10 Upgrade was activated, then proceed to perform a Reset.

Starting with versions Windows 10 1511 or later, users no longer have to go through this process.

What is the Digital Entitlement or Digital License?

When you upgrade from a previous version of Windows, what happens is the hardware, (your PC), will get a digital license. This is a unique signature of the computer which is stored on Microsoft Activation Servers. The Windows 7 or Windows 8 genuine license you were previously running will be exchanged for a diagnostics product key.

Anytime you need to reinstall Windows 10 on that machine, just proceed to reinstall Windows 10. It will automatically reactivate. The only exception where this applies is dependent on the license you upgraded from. If you change your motherboard and originally you upgraded from a Windows 7 OEM or Windows 8 OEM license, then your Digital Entitlement will be invalidated. You will need to purchase a new full version license.

Buy Windows 10 Home/Pro

So, there is no need to know or get a product key, if you need to reinstall Windows 10, you can use your Windows 7 or Windows 8 product key or use the reset function in Windows 10.

Learn more: How to install and activate Windows 10 using your Windows 7 or Windows 8 product key

Perform a Clean Install on an Empty Hard Disk/SSD or Reinstall by Booting from Install Media (DVD or USB Thumb Drive)

Once you have your Windows 10 installation media ready, all you need to do is boot from the disc or USB thumb drive to begin setup. If you don't have install media, see instructions: How to download official Windows 10 ISO files 

Review the following guide for instructions and details about configuring your BIOS or UEFI boot settings for DVD, CD, USB or SD Card.

BIOS/UEFI Setup Guide: Boot from a CD, DVD, USB Drive or SD Card

Once your computer is set to boot from the DVD, you should see this option. If you are installing from a retail Windows 10 USB thumb drive, you will be asked to select either 32 or 64 bit Windows 10. Learn more here

The Windows logo will appear on screen, this might be here for a while, as long as you see the animating dots, everything should be ok.

Select your Language, Time and Keyboard method then click Next.

Click Install now

Windows 10 setup will prompt you for a product key during installation a couple times. If you originally upgraded from Windows 7 or Windows 8/8.1 click the option 'I don't have a key' and 'Do this later' . If you have a Windows 10 product key, you can proceed to enter it.

Setup will also prompt you to select the edition you have a license for - Home or Pro. Please make sure you choose the right edition. If you choose the wrong edition, your only option will be to perform a clean install again.

The copy of Windows 10 you download and upgrade from will correspond with the edition of Windows you have installed, if it does not, this is why you might be experiencing problems activating:

  • Windows 7 Starter, Home Basic, Home Premium, Windows 8.0 Core, Windows 8.1 Core should install Windows 10 Home 

  • Windows 7 Professional, Windows 7 Ultimate, Windows 8.0 Pro, Windows 8.1 Pro should install Windows 10 Pro

Wait while setup prepares to copy files

Accept the license terms then click Next

Click Custom: Install Windows only (advanced) 

NOTE: Sometimes Windows 10 setup can become confused if it see's a thumb drive. You might get a driver missing error or something to that effect. If you do, restart setup, but this time, when you arrive at the following screen, disconnect your thumb drive then go through Custom options. When setup is ready copy files, it will prompt you to reconnect the installation source (your USB). 

Select the drive then click New

NOTE: If you have multiple partitions listed, select each one (starting at the bottom), then click delete until there is only a single (one) unallocated drive displayed in the window.

Select the unallocated drive listed, click New, click Apply then OK

This will split the drive into multiple partitions, select the Primary partition then click Next.

NOTE: The System Reserved partition is where recovery files are kept for diagnostics and repairing damaged Windows 10 files; or even reinstall Windows 10.

Wait while Windows installs

When this phase of setup is complete, Windows will automatically restart then reboot into setup again.

Windows is detecting and installing your hardware. After this is complete, Windows will restart one last time.

Out of Box Experience

The Out of Box Experience page is where you get to configure detailed settings in Windows, which includes creating a user account, configure privacy, sync PC settings and install modern applications.

Learn more about setting up your Windows 10 Installation:

How to Setup and Configure a New Windows 10 PC

There you go, Windows 10 has successfully installed!

Install the Latest Windows Updates immediately

Start > Settings > Update and Security > Windows Update then click Check for Updates

Perform a Clean Install Using Reset, Recovery Drive or Refresh Tools (Start Fresh) in Windows 10

If you already have Windows 10 installed, you can use the built in Reset function, Recovery Drive or Refresh Tools (Start Fresh) in Windows 10 do so. Learn how in the following article:

How to: Perform a clean install using Reset this PC in Windows 10

How to: Create a Recovery Drive for reinstalling Windows 10 

How to Perform a Clean Install of Windows 10 with the Refresh Tool

How to Perform a Clean Install by Starting Setup from Within a Running Version of Windows 10

If you are running Windows 7 or Windows 8.0, Windows 8.1 or Windows 10, launch Windows 10 setup using ISO Media:

During setup, at the Ready to install screen, click Change what to keep link

Select Nothing

Click Next to being the installation

How do I check my activation status?

Click Start > Settings (press Windows key + i) > Update & security > Activation

Depending on the version of Windows 7 installed, 1507, 1511, 1607, you will see different wording beside the activation status:

Windows 10 1507 (build 10240)

Windows 10 1511 (build 10586)

Windows 10 1607 (build 14393) or later.

If you experience problems with product activation, please review:

How To troubleshoot Product Activation in Windows 10


How to: Install and Update drivers in Windows 10

How to: upgrade from previous versions of Windows using Windows 10 ISO file

* Please try a lower page number.

* Please enter only numbers.

* Please try a lower page number.

* Please enter only numbers.


Fantastic article. Very clear. However, I'm having a problem that is not addressed in your step-by-step guide.

I successfully get to the step right before the OOBE. My PC boots again but goes back to the DVD which is still inserted. Then, I get the prompt to Press any key to reboot from CD or DVD. Doing so gets me back to the setup on the DVD for another install. Not hitting any key causes my PC to just stop.

Is the media supposed to be removed prior to this final reboot?


[UPDATE] Success. By a combination of doing a PC Cleanup then removing the DVD just after the final setup step, I'm able to boot into the Tech Preview and finish setting up accounts, etc. I'm up and running now.

Strange, what is your default boot device in the BIOS, hard disk or DVD?

Try making your hard disk be the default boot device in the BIOS and see if allows you to boot into Windows 10 without going into setup again.

Windows Insider MVP
MVP-Windows and Devices for IT

I'm not sure what you mean by "default boot device". My boot order is DVD then hard drive. If I make the hard drive first then I cannot boot from the DVD to get the install started.

The hard drive had an old Windows 8.0 system on it. When I tried to install a bunch of updates, I could no longer boot from the hard drive. That's when I decided to just scrap 8.0 and try Win 10.

But I'm not sure that's my problem. If I pull the DVD and try to boot off the hard drive I get this error, in plain text on a black background:

A disk read error occurred

Press Ctrl+Alt+Del to restart

When I do that, I get the same thing again.

If you are in the OOBE for Windows 10, why would you need to be booting from the Windows 10 install media again except for installing Windows 10 again?

What you said:

I successfully get to the step right before the OOBE.

This is right before the OOBE:

When this phase of setup is complete, Windows will automatically restart and reboot into setup again.

Which means, all necessary files would have already been copied from the disc to facilitate the installation.

Do you have more than one hard disk installed in your computer?

Do you have external storage devices attached to the system?

If you do, disconnect them before running setup.

Windows Insider MVP
MVP-Windows and Devices for IT

Andre, I'm not in the OOBE. As I said, and you quoted, I'm in the step before where I see the "Windows needs to restart .." message. But because my DVD player is first in line in my BIOS, instead of booting to my hard drive which now has the Tech Preview on it, the PC boots back to the DVD with the install ISO on it.

But, as I said in the update to my first post above, I was able to pull the DVD in time so my PC booted to the hard drive. I now have the Tech Preview running.

Thanks for the article and your help.


Understand but we need a iso or a file that can burn a disk the main operating system. where form we get it? 


Thanks for writing this up.  Disappointed to hear that I cannot use the upgrade to do a clean install initially.  Hope that changes, but probably won't hold my breath..  ;-)


Well, I have a question:

I did the free upgrade of my Windows 7 and now want to reinstall Windows 10 using a clean install. I'm a bit anxious from nature so I first looked up whether my installation of Win10 is activated and which product key is used.

And that's the strange part:

When I use the MGADiag.exe tool to check genuinity of the installation it shows me a key that ends exactly like the Windows 10 Insider Preview Key. More curious:

Using a 'key extractor vb-script':

Set WshShell = CreateObject("WScript.Shell") MsgBox ConvertToKey(WshShell.RegRead("HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\DigitalProductId")) Function ConvertToKey(Key) Const KeyOffset = 52 i = 28 Chars = "BCDFGHJKMPQRTVWXY2346789" Do Cur = 0 x = 14 Do Cur = Cur * 256 Cur = Key(x + KeyOffset) + Cur Key(x + KeyOffset) = (Cur \ 24) And 255 Cur = Cur Mod 24 x = x -1 Loop While x >= 0 i = i -1 KeyOutput = Mid(Chars, Cur + 1, 1) & KeyOutput If (((29 - i) Mod 6) = 0) And (i <> -1) Then i = i -1 KeyOutput = "-" & KeyOutput End If Loop While i >= 0 ConvertToKey = KeyOutput End Function

I got even another key which is neither my Win7 key nor the Insider Preview key.

[Update]I now upgraded a 2nd Windows7 license too and it has the same key when extracted, seems to be generic[/Update]

What key should I put in when I'm prompted to activate Windows 10 after the clean install?

I DID NOT use a Microsoft Account - and I won't be persued to do so.

I have the same problem ? Which key to use after installation ? Win 7 , Win 8.1 and now Win 10

Instead of publishing a new article, how about answering the questions?


When I upgrade to Win10 my Hardware-Setup is recorded in a MS DB and connected with a free license for Win10.

What, when my hardware changes? Yes there's much information about that but only from 3rd-party. Do I need to do the upgrade again? What if my hardware changes AFTER the one year after the release? Do I still get the free upgrade? If not, can I at least use my 'old' Windows which I before used to upgrade to Win10 or is the license not valid anymore (you say one can only 'go back' 30days lonng).

How's all that with Germany: Here a hardware-change afaik cannot 'invalidate' the license. So: Do *we* get Win10 for free on all devices?

All questions not have been answered by MS Officials.

This, well, is quite sh*t.

* Please try a lower page number.

* Please enter only numbers.

* Please try a lower page number.

* Please enter only numbers.


Forum Article Info

Last updated November 25, 2020 Views 1,251,637 Applies to: