How to clean install from Windows 7 Upgrade media

One of the biggest unanswered questions about Windows 7 is whether you can perform a clean install using the upgrade edition of the operating system.

With legacy versions of Windows you needed to ‘show’ it an install CD from your older version of Windows.  The problem here is that Microsoft allowed OEM PC makers to customise these discs, sometimes to the point where they were not recognisable as upgrade media by the installer, even though you had a legitimate copy.


With Windows Vista they changed this but you had to perform a workaround to get a clean install.  Firstly you had to install Vista upgrade without entering a product key, and then you had to install it again performing an upgrade on the version you had already installed.  This was time-consuming and many people didn’t like it… understandably.

With Windows 7 Microsoft have only released the upgrade versions for the first time today and have been keeping very tight-lipped on this subject.  The good, nay, excellent news is that performing a clean install using upgrade media is now the same as performing a clean install.

Windows 7 will just install merrily on your hard disk with it’s upgrade product code and activate.  You don’t need an XP or Vista disc, and you don’t need to install it over itself.  This is excellent news and, while I haven’t yet tried this myself, reports are coming in from across the web that this is indeed the case.

Many people will now ask if it’s necessary to buy the full version of Windows 7.  Quite simply now the answer is that it isn’t.  This means an significant price cut for Windows 7 over previous versions, effective immediately.


While it is not necessary to buy a full version of Windows 7 it is still a legal requirement to do so if you do not own a legal copy of either Windows XP or Windows Vista. The article did not make that completely clear. (Martin)

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54 Responses to How to clean install from Windows 7 Upgrade media

  1. Tim from Kent October 23, 2009 at 1:16 pm #

    Did not work for me

  2. Anonymous October 23, 2009 at 2:27 pm #

    Fantastic post – Have been waiting to hear on this subject for a long long time. I will have to test it though (Might receive my upgrade media any day now)…. Update 0ct 24: I just followed instructions per Paul thurott’s post (…) — It workslike charm.

  3. Anonymous October 23, 2009 at 3:06 pm #

    Then why does the full version even exist? This sounds too good to be true.

  4. Dom October 23, 2009 at 7:25 pm #

    Someone needs to QA this article. I just called Microsoft after NOT being able to clean install using my Upgrade media, and they stated the ONLY way you can perform a clean install is using a full retail copy. Some are having issues, while others are not. Someone is not telling the whole story here.

  5. jkvato October 23, 2009 at 9:19 pm #

    It’s not to Microsoft’s advantage to advertise these workarounds, so I’m not surprised that they told you they can’t do it. For months, MS has been saying that you have to have an activated OS on your hard drive in order to use an Upgrade version of Win 7.

    There are other, similar workarounds that have been reported on the Internet. Take a peek at Paul Thurrott’s site at He has a post or two that explain how to do this.

    All I know is that I did install an Upgrade Win 7 on a clean hard drive without older CD’s or product keys. I did have to install it twice, however — which was lengthy. Thurrott has apparently found an even quicker way to do it.

  6. Name October 24, 2009 at 7:39 am #

    clean install worked fine for me. Converted student Win7 Pro to a bootable iso and booted with it. I selected custom, wiped the previous rtm 7 ultimate that was never activated and selected activate when I’m on line. After first boot activation said it would take place in three days. I pressed activate now and it activated with now problem.

  7. kabel October 24, 2009 at 11:13 pm #

    Clean install should work since they advertise it:

    I bought brand spanking new ssd and got the same crap with the key not being valid. I called Microsoft and after two hours talking, they finally connected me with some rep. that knows something and he told me the same trick Paul Thurrott posted. I finally got my smile back after that crap with the key not being valid.

  8. Erik October 24, 2009 at 11:32 pm #

    So when promted to enter the key you can go around it and get into windows 7 simply to do Paul Thurrot’s Trick then validate it through utility manager?

    • kabel October 25, 2009 at 10:51 am #

      I activated my Windows 7 Pro with help from Microsoft Rep. I didn’t know about Paul Thurrot’s Trick until late night yesterday.
      The difference between Win7 and Vista is that when you do slmgr.vbs -dlv, Windows 7 tells you how many times you can rearm (slmgr.vbc -rearm) your license manager; Vista does not display that information. Be careful with this rearm command.

  9. Frank B October 29, 2009 at 5:42 am #

    Thanks microsoft for saving me money…

    I used to love to expirement with computers. Try new hardware, new software. I used to spend $1000.00s on software and hardware but no more. Now it is not possible to do with windows. The amount of time it takes to install the OS all of the upgrades. What used to take a few hours now takes days. Although i understand why they have to do it the activation is also another obstacle.

    I dred having to upgrade the OS. I wish i would have had the forsite to change to linux long ago. Now all of my apps are windows and i am stuck. But hey, at least my net worth is greater.

  10. Eric Ligman November 1, 2009 at 4:00 pm #

    Thank you for the update to the original article, Martin. That is an important component to call out about needing a full license of Windows XP or Windows Vista to legally qualify for the Upgrade.

  11. Jane Maritz December 21, 2009 at 4:48 pm #

    What’s the deal with 64-bit upgrades? I did a clean install on a PC already running 64-bit, with no problem. Now I’m trying to do a clean install of Win7 64-bit on a PC running a 32-bit OS. If I try to run the install from Windows, it says it’s incompatible with the current system. If I try to boot from the CD, it doesn’t recognize it and goes on to boot from the hard drive.

    Tried this on 2 different computers with 32-bit OS, and tried it with a downloaded upgrade CD and an upgrade CD straight from Microsoft.

  12. Anonymous February 20, 2010 at 11:37 am #

    Working Installation: Turn-off your net connection and enter product key
    Nightmare: Install online

  13. best registry cleaner August 27, 2010 at 3:32 am #

    # Delete unused, old or duplicate files, emails, email addresses, bookmarks and favorites.
    # Organize your files. Make sure to use a logical file naming system and put them into folders that make sense and are easy to remember and access.
    # Uninstall programs that you no longer need or use.
    # Further improve your computer’s start-up time by removing unnecessary start-up items.
    # Don’t forget your PC’s outside. Clean the screen, dust the keyboard, clean the mouse. After all, your computer deserves some pampering too.

  14. Anonymous October 4, 2010 at 11:38 pm #

    I must say, you have this down to a science my friend.

  15. Best Registry Cleaner December 5, 2010 at 1:28 am #

    Microsoft isn’t going to let you do an upgrade if it doesn’t have some indication that you have a previous version of windows.

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