How to Format C From a Windows Setup Disc

It's easy to format the C drive from the Windows setup process

What to Know

  • Boot from the Windows Setup DVD and start installing Windows. Choose I don't have a product key if asked.
  • Select Custom: Install Windows only (advanced), choose the C drive, then select Format.
  • Formatting your drive this way doesn't completely erase the information on the drive.

This article explains how to format your C drive with a Windows Setup DVD. You must use a Windows Setup DVD with Vista or newer on it to format C this way. It doesn't matter what operating system is on your C drive (Windows XP, Linux, Windows 11, Windows Vista, etc.)

How to Format C From a Windows Setup Disc

This is easy, but it will probably take several minutes or longer to format C using a Windows Setup disc. Here's how.

  1. Boot from the Windows Setup DVD.

    Watch for the Press any key to boot from CD or DVD message after your computer turns on and be sure to do that. If you don't see this message but instead see the Windows is loading files message, that's fine, too.

    You will not be installing Windows and will not need a product key. You'll stop the setup process before Windows begins to install on the computer.

  2. Wait for the Windows is loading files and the Starting Windows screens. When they end, you should see the big Windows logo with several drop-down boxes.

    Change any language, time, or keyboard options if you need to and then select Next.

    Windows 10 setup disc start screen

    Don't worry about the "loading files" or "starting Windows" messages being literal. Windows is not being installed anywhere on your computer—the setup program is starting, that's all.

  3. Choose Install now and then wait during the Setup is starting screen. Again, don't worry—you won't really be installing Windows.

    If you're using the Windows 7 install disc, you can skip down to Step 6.

  4. If you see a screen about activating Windows with a product key (like on the Windows 10 setup disc), select I don't have a product key.

  5. If you see a screen asking which version of the operating system you want to install, select one and then choose Next.

    Windows Setup screen with a list of Windows 10 versions
  6. Accept the terms by putting a check in the box next to I accept the license terms, and then press Next.

  7. You should now be on the Which type of installation do you want window. This is where you'll be able to format C. Select Custom: Install Windows only (advanced).

    If you're using the Windows 7 disc, choose Custom (advanced) followed by Drive options (advanced).

  8. As you can see, several options are now available, including Format. Since we're working from outside of the operating system installed on your computer, we can now format C.

  9. Choose the partition from the list that represents your C drive and then choose Format.

    Windows Setup disc format drive options

    The C drive will not be labeled as such. If more than one partition is listed, be sure to choose the correct one. If you're not sure, remove the Windows Setup disc, boot back into your operating system, and record the hard drive size as a reference to figure out which partition is the correct one. You can do that by following his tutorial.

    If you choose the wrong drive to format, you could be erasing data you want to keep!

    Some operating systems create more than one partition during setup. If your intention for formatting C is to remove all traces of an operating system, you may want to delete this partition, and the C drive partition, and then create a new partition that you can then format.

  10. After selecting Format, you're warned that what you're formatting "...might contain important files or applications from your computer manufacturer. If you want to format this partition, any data stored on it will be lost."

    Take this seriously! As pointed out in the last step, it's very important that you're sure this is the C drive and that you're sure that you really do want to format it.

    Select OK.

  11. Your cursor will turn busy while Windows Setup is formatting the drive.

    When the cursor turns back into an arrow, the format is complete. You're not otherwise notified that the format is over.

    You can now remove the Windows Setup DVD and turn off your computer.

When you format C, you remove your entire operating system. This means that when you restart your computer and attempt to boot from your hard drive, it will not work because there's no longer anything there. What you'll get instead is a BOOTMGR is missing or an NTLDR is missing error message, meaning there was no operating system found.

Tips & More Help

When you format C from a Windows setup disc, you don't truly erase the information on the drive. You only hide it (and not very well) from a future operating system or program!

This is because a format performed this way from the setup disc is a "quick" format that skips the write-zero portion performed during a standard format.

If you want to actually erase the data on your C drive and prevent most data recovery methods from being able to resurrect it, you'll need to wipe your hard drive.

If you don't have a Windows Setup DVD, there are other ways to format the C drive.

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