I want to format a PC, but I don't know what the OS install credentials are. The PC got Windows 10 from that update a few years ago, I did not install Windows 10 myself.

I would like to keep the OS after the format though, I just don't know the credentials to install the OS again. Is there a program that can give you the OS keys of the PC you are on?

  • Did you try Windows Utilities? recover-keys.com
    – onurcano
    Commented Mar 21, 2018 at 9:46
  • 1
    If Win10 was originally installed using the downgrade offer from Win7 or 8, just use that very same serial, as it was "converted" to Windows 10 too. There won't be a new serial for that install, as the key is the very same of the earlier version it came from.
    – Alejandro
    Commented Mar 21, 2018 at 12:37
  • aah I see, did not know that.
    – Neil Meyer
    Commented Mar 21, 2018 at 13:29
  • If you registered for the free upgrade from an earlier version and your hardware is the same (more specifically, provided a number of different ID data in the firmware is the same and the hardware otherwise looks the same), then you don't need a license key, just install Windows 10 and it will activate automatically. Same goes for many more recent laptops (which have the license key embedded in the firmware). Commented Mar 23, 2018 at 17:07

3 Answers 3


Windows10 remembers your computer, once succesfully activated it will recognize the hardware automatically, as long as you do not make serious (hardware) changes between. Make sure you install the same Windows edition as was installed before.


A free program, Belarc Advisor, provides a summary of your computer, including product keys for almost everything on the machine (a few exceptions, I'm sure). I have now installed it on my Win10 test box and it returned my Win10 product key.

Other features of the program may be of use as well.


You can use MSKeyViewer Plus.

MSKeyViewer Plus is free and portable. It shows license keys for installed MS products and additionally other third party applications as well. Download link provided here

Not the answer you're looking for? Browse other questions tagged or ask your own question.