How To Clean Install Windows 7

Print Friendly, PDF & Email

Very detailed instructions. Please pay specail attention on how to wipe the disk clean, during installation.

Original text and author

Screenshot of the Windows 7 splash screen -

Windows 7 Clean Install – Step 1 of 34.

A Windows 7 clean install simply means an installation of Windows 7 on an unused partition on your hard drive. In most cases, though, a clean install of Windows 7 means to remove an existing operating system (Windows XP, Linux, Windows 7, Windows 8, … doesn’t matter) and to replace it with a fresh installation of Windows 7.

After serious Windows 7 problems or during a new Windows 7 installation with an older operating system installed that you’d like to replace, it’s best to wipe your primary hard drive partition clean and reinstall Windows 7 from scratch – a procedure referred to as a “clean install” or sometimes as a “custom install”.

This guide is broken into 3 parts for a total of 34 steps and will walk you through every part of the Windows 7 clean install process.

Backup & Locate Your Product Key

The most important thing to realize before performing a clean install of Windows 7 is that all of the information on the drive that your current operating system is installed on (probably your C: drive) will be destroyed during this process. That means that if there’s anything you want to keep you should back it up to a disc or another drive prior to beginning this process.

You should also locate the Windows 7 product key, a 25-digit alphanumeric code unique to your copy of Windows 7. If you can’t locate it, there is a fairly easy way to find the Windows 7 product key code from your existing Windows 7 installation, but this must be done before you reinstall Windows 7.

Note: If Windows originally came preinstalled on your computer (i.e. you did not install it yourself), your product key is probably located on a sticker attached to the side, back, or bottom of your computer’s case.

This is the product key you should use when installing Windows 7.

Start the Windows 7 Clean Install Process

When you’re absolutely sure sure that everything from your computer that you want to keep is backed up, proceed to the next step. Keep in mind that once you delete all of the information from this drive (as we’ll do in a future step), the action is not reversible!

Note: The steps and screen shots shown in these 34 steps refer specifically to Windows 7 Ultimate edition but will also serve perfectly well as a guide to reinstalling any Windows 7 edition you may have including Windows 7 Professional or Windows 7 Home Premium.

Performing a Clean Install of an OS Other Than Windows 7?

See How Do I Perform a Clean Installation of Windows? for specific instructions for your version of Windows.

Boot From the Windows 7 DVD or USB Device

Screenshot of the Press any key to boot from CD or DVD screen -
Windows 7 Clean Install – Step 2 of 34.

To begin the Windows 7 clean install process, you’ll need to boot from the Windows 7 DVD if you’re using a Windows 7 DVD, or boot from a USB device if your Windows 7 installation files are located on a flash drive or other externalUSB drive.

Tip: See the How To Change From One Windows 7 Installation Media To Anothersection at the bottom of the page if you have a Windows 7 ISO image that you need on a flash drive or disc, or a Windows 7 DVD you need on a flash drive.

  1. Restart your computer with the Windows 7 DVD in your optical drive, or with the properly configured Windows 7 USB flash drive plugged in.
  2. Watch for a Press any key to boot from CD or DVD… message similar to the one shown in the screenshot above. If you’re booting from a flash drive, the message may be phrased differently, like Press any key to boot from external device….
  3. Press a key to force the computer to boot from the Windows 7 DVD or USB storage device. If you do not press a key, your PC will attempt to boot to the next device in the boot order, which is probably your hard drive. If this happens, chances are your current operating system will boot.

Note: If you existing Windows installation begins to boot or you see a “No Operating System Found” or “NTLDR is Missing” error here instead of the screen above, the most probable reason is that your PC is not setup to boot first from the correct source. To correct this problem, you’ll need to change the boot order in BIOS to list the CD/DVD/BD drive, or External Device, first.

Note: It’s perfectly fine if, instead of the screen above, the Windows 7 setup process begins automatically (see the next step). If this happens, consider this step complete and move on.

How To Change From One Windows 7 Installation Media To Another

With both ISO and DVD options available when purchasing Windows 7, as well as the growing number of smaller computers without optical drives, you may find that, in order to start your clean install, you need to get your Windows 7 installation files from whatever format or media they’re on now onto another.

Here are some common problems that I see people in when planning to clean install Windows 7, plus easy to follow solutions:

“I have a Windows 7 DVD but don’t have an optical drive, so I need to be able to install Windows 7 from a flash drive.”

This is the most common problem I see. The solution involves properlyformatting a flash drive, or any USB storage device, and then correctly copying the Windows 7 installation files from the DVD disc to the flash drive.

See How To Install Windows 7 From USB for a complete walkthrough of that process, then come back here to continue with the clean install.

“I downloaded a Windows 7 ISO file but I need to install Windows 7 from a USB drive.”

Similarly to the last question, your final goal is to get the Windows 7 installation files, which are stored in that ISO file you have, to a flash drive or other external drive.

You get to use the same How To Install Windows 7 From USB tutorial as in the last question, only you get to skip a step.

“I have a Windows 7 ISO file but I need to install Windows 7 from a DVD.”

This problem is easy to solve, as there’s a very straightforward way of properly burning ISO images to discs, like CDs, DVDs, and BDs.

See How To Burn an ISO File to a Disc for help and then head back here for the rest of the Windows 7 clean install tutorial.

Note: You can’t just burn an ISO file to a disc like you would with other data. If you’ve never burned an ISO image before, be sure to check out the tutorial.

Wait for Windows 7 Installation Files to Load

Screenshot of Windows 7 setup loading files -
Windows 7 Clean Install – Step 3 of 34.

You don’t need to do anything at this point but wait for Windows 7 to finishing loading files in preparation for the setup process.

Note: No changes are being made to your computer at this time. Windows 7 is just temporarily “loading files” into memory for the setup process. You’ll be removing everything on your computer as part of the Windows 7 clean install in a future step.

Wait for Windows 7 Setup to Finish Loading

Screenshot of the Windows 7 splash screen -
Windows 7 Clean Install – Step 4 of 34.

After the Windows 7 install files are loaded into memory, you’ll see the Windows 7 splash screen, indicating that the setup process is about to begin.

You don’t need to do anything at this point.

Choose Language and Other Preferences

Screenshot of Windows 7 setup asking you to Choose Language and Other Preferences -
Windows 7 Clean Install – Step 5 of 34.

Choose the Language to install, Time and currency format, and Keyboard or input method that you’d like to use in your new Windows 7 installation.

Click Next.

Click the Install Now Button

Screenshot of the Windows 7 setup -
Windows 7 Clean Install – Step 6 of 34.

Click on the Install now button in the center of the screen, under the Windows 7 logo.

This will officially begin the Windows 7 clean install process.

Note: Do not click the Repair your computer link at the bottom of the window even if you’re completing this clean install of Windows 7 as part of some larger repair project for your computer.

The Repair your computer link is used to start a Windows 7 Startup Repair or perform another recovery or repair task from System Recovery Options.

Important: If you’re performing a clean install of Windows 7 as a solution to a major problem but have not yet tried a Startup Repair, do that first. It could save you the trouble of completing this clean install process.

Wait for Windows 7 Setup to Begin

Screenshot of Windows 7 setup starting up -
Windows 7 Clean Install – Step 7 of 34.

The Windows 7 setup process is now beginning.

No need to press any keys here.

Accept the Windows 7 License Terms

Screenshot of the Windows 7 License Terms during setup -
Windows 7 Clean Install – Step 8 of 34.

The next screen that appears is a textbox containing the Windows 7 Software License.

Read through the agreement, check the I accept the license terms checkbox under the agreement text and then click Next to confirm that you agree with the terms.

Note: You should always read “small print” especially when it comes tooperating systems and other software. Most programs, Windows 7 included, have legally binding limits on how many computers the application can be installed on, among other limitations.

Important: You are not breaking any laws or contracts by reinstalling Windows 7 via this clean install. As long as this particular copy of Windows 7 is only being operated on one computer, you’re OK.

Choose the Type of Windows 7 Installation to Complete

Screenshot of the Which type of installation do you want? screen during Windows 7 setup -
Windows 7 Clean Install – Step 9 of 34.

In the Which type of installation do you want? window that appears next, you’re offered the choice of Upgrade and Custom (advanced).

Click on the Custom (advanced) button.

Important: Even if you are upgrading from a previous operating system toWindows 7, I highly recommend that you do not follow the Upgrade installation. You’ll get better performance with less chance of issues if you follow these clean install steps.

Show the Windows 7 Advanced Drive Options

Screenshot of the Where do you want to install Windows? screen during setup -
Windows 7 Clean Install – Step 10 of 34.

In this screen, you’ll see each partition that Windows 7 recognizes.

The main difference in a Windows 7 clean install verses other kinds of Windows 7 installation methods is that a clean install involves the removal of alloperating system related partitions.

Windows 7 setup considers partition management as an advanced task so you’ll need to click the Drive options (advanced) link to make those options available.

In the next few steps you’ll delete the partitions containing the operating system you’re replacing with Windows 7, be it Windows Vista, Windows XP, a previous installation of Windows 7, etc.

Delete the Partition Windows is Installed On

Screenshot of deleting a partition to install Windows 7 -
Windows 7 Clean Install – Step 11 of 34.

Now that all available drive options are listed, you can delete any operating system related partitions from your existing hard drive(s).

Important: Before continuing, be aware that deleting a partition will permanently erase all data from that drive. By all data I mean the operating system installed, all programs, all data saved by those programs, all music, all video, all documents, etc. that might be on that particular drive.

Highlight the partition you want to delete and then click the Delete link.

Note: Your list of partitions may differ considerably from mine shown above. On my computer, I am performing a clean install of Windows 7 on a computer with a single 30GB hard drive that has previously had Windows 7 installed.

If you have multiple hard drives and/or multiple partitions on those drive(s), take great care in confirming that you’re deleting the correct partition(s). Many people, for example, have second hard drives or partitions that act as backup drives. That’s certainly not a drive you want to be deleting.

Confirm the Partition Deletion

Screenshot of deleting a partition during the Windows 7 setup -
Windows 7 Clean Install – Step 12 of 34.

After deleting the partition, Windows 7 setup will prompt you to confirm the deletion.

The message says “The partition might contain recovery files, system files, or important software from your computer manufacturer. If you delete this partition, any data stored on it will be lost.”

Click the OK button.

Important: As I spelled out in the last step, please be aware that all the data stored on that drive will be lost.

If you have not backed up everything you want to keep, click Cancel, end the Windows 7 clean install process, restart your computer to boot back into whatever operating system you have installed, and backup everything you want to keep.

To be clear: This is the point of no return! There’s no reason to be scared, I just want it to be very clear that you can’t undo the deletion of the drive you selected after you click this OK button.

Delete Other Operating System Related Partitions

Screenshot of deleting partitions during Windows 7 setup -
Windows 7 Clean Install – Step 13 of 34.

If there are any other partitions that need to be deleted, you can do so at this time.

For example, the Windows 7 installation I had on my PC previously created this special 100MB (very small) partition to store system data in. This is most definitely related to the operating system that I’m trying to completely remove from my computer so I’ll delete this as well.

Highlight the partition and click the Delete link.

Note: As you can see, the partition we deleted in the last step is gone. It may appear like it’s still there but if you look closely, you’ll see that that same 29.9GB space is now described as Unallocated Space, not as a partition.

Confirm Additional Partition Deletions

Screenshot of deleting partitions during the Windows 7 setup -
Windows 7 Clean Install – Step 14 of 34.

Just as in Step 12, Windows 7 setup will prompt you to confirm the deletion of this partition.

Click the OK button to confirm.

Important: Just as before, please be aware that all the data stored on this particular drive will be lost.

Choose a Physical Location to Install Windows 7 On

Screenshot of choosing a hard drive to install Windows 7 to -
Windows 7 Clean Install – Step 15 of 34.
As you can now see, all the space on the installed hard drive is unallocated. Nopartitions exist on this computer.Note: The number of partitions displayed and whether those partitions are unallocated portions of a hard drive, previously partitioned spaces, or previously formatted and blank partitions will depend on your specific system and which partitions you deleted in the last several steps.If you’re installing Windows 7 on a computer with a single hard drive on which you’ve just deleted all the partitions from, your screen should look like the one above, aside from your hard drive being a different size.Choose the appropriate unallocated space to install Windows 7 on and then clickNext.Note: You do not need to manually create a new partition nor are you required to manually format a new partition. Windows 7 Setup will do this automatically.This completes Part 1 of 3!

Leave a Reply