I have Windows 7 installed in my computer. Now I want to reinstall it. I have 500 MB free of 19 GB on my C drive. When it comes to the step of selecting a drive to install the OS, it says the C drive does not have enough space. But the concerning issue is it does not show any Format option either, so I cannot reinstall Windows 7.


You need to delete both partitions when you get to that screen so that you see one whole Unallocated space.

There should be a Drive Options (advanced) button/link in middle-right.

You can refer to the resources below:

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Are you currently logged into your Windows OS while doing this or did you Boot from disc?

There is also a note at the bottom: Windows cannot be installed to Disk 0 Partition 1. (Show Details) so I would like to know, what are those details?


I used to like the GUI of the installer. Until making a new partition:


Then select max size and click Apply, this popup i most want to avoid:

ApplyPopup 2PartitionsNow

If you are fine with the wasted 100MB partition, do this from beginning:

Click the Repair your computer link near bottom left:


When it finished loading, select Use recovery tools... and click Next:


Click Command Prompt link:


In the command window, type diskpart and press Enter. See DiskPart command line options:


I now assume you want Windows 7 to take on single partition on Disk 0. Lines you need to type:

select disk 0
create partition primary
assign letter=c
format fs=ntfs quick

Now 1 single active primary partition is ready and formatted as ntfs, close the System Recovery Options window to return to first screen, click Install now.

For Type of Installation, click Custom (advanced). Then click Next (notice the partition is type "System"):


  • In your first image/screenshot why are you creating a new partition if all you have is one whole disk with 127.0 GB unallocated space. Just click the Next button and install Windows – MonkeyZeus Nov 8 '13 at 13:55
  • If you do that, it will create a 100MB "System Reserved" partition. – PatricK Nov 8 '13 at 20:23
  • I can see that you are quite experienced with managing partitions but won't the Installation process still create the 100MB partition if you hit Next in your final screenshot? Maybe I'm not fully understanding what you're trying to achieve especially since it is generally not recommended for people to remove that partition. technet.microsoft.com/en-us/magazine/gg441289.aspx and answers.microsoft.com/en-us/windows/forum/windows_7-performance/… – MonkeyZeus Nov 8 '13 at 20:42
  • The method I described won't create the 100MB system reserved partition. The gui does not create it if the selected partition is Active. Which is not accessible. This method is used mostly in business advanced users where IT Support are available if things go wrong. – PatricK Nov 10 '13 at 5:23

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