Reformat Windows 7 Hard Drive

Category: Hard-Drives , Windows-7

If you need to reformat a hard drive using Windows 7, the method you should use depends on whether you want to reformat a bootable drive or a secondary drive. Here are the steps for both procedures...

How to Reformat Your Hard Drive on Windows 7

I know, I promised to tell you how to reformat a hard drive (or a drive partition) on a PC that's running Windows 7. But first, I think it's important to let you know why that might not be the best solution.

Reformatting is drastic. It will wipe your drive clean of ALL files, and afterwards you'll have to restore any important files from a backup. And if the drive is a boot drive, you'll also have to re-install the Windows operating system.

All of that can take many hours. So if you're frustrated with a computer that seems to be running slower than normal, or if you've run into a problem with viruses or spyware, read each of the articles below before resorting to a reformat. Doing so just might help you clean up and speed up your system, and change your mind about formatting.
Reformat Windows 7 Hard Drive

Formatting a Secondary Drive or Partition

Okay, so you really want to reformat your drive. Let's handle the case of a secondary drive first, since it's simpler. I'm defining a secondary drive as a hard drive or a drive partition that is not bootable. It exists just to store files, but it doesn't have the operating system installed on it. If you have just one physical hard drive, a secondary drive could be a partition on that drive marked as D:, E:, etc. A secondary drive could also be a second physical drive installed inside your computer, an external hard drive, or a USB flash drive.

To reformat a secondary drive, simply right-click on its icon in the Computer view and select Format. The dialogue box that pops up will show the drive's capacity in megabytes. You will also see four options that you can specify.

  1. The "File System" is the method used to organize disk space and keep track of where files are stored. You should use NTFS with Windows 7, unless you have a specific need for an older file system. USB flash drives, for instance, perform best with the FAT16 file system.
  2. "Allocation Unit Size" is the number of bytes allocated to each sector of the drive. Use the standard allocation unit size for NTFS (4,096 bytes) unless you have a good reason to change it. The "restore device defaults" button sets the file system and allocation unit size to the values that Windows automatically determines are optimal for the device in general-purpose use.
  3. The "volume label" is any name that you wish to give to the drive. The volume label will appear next to the drive's icon and the drive letter that is assigned to it by Windows.
  4. Check the "quick format" box if you are in a hurry and do not need a bootable drive. A quick format does not format every sector on the drive; it just wipes the existing file system and writes a new one to your specifications. Data formerly stored on the old drive is not actually erased, it is simply ignored and written over after reformatting. If you do not select "quick format", a full format will be done, which can clean up any corrupted sectors on a hard drive.

Click the "Start" button when you are ready. A quick format takes only a couple of minutes, while a full format can run for hours. When the format ends, close the Format dialogue box. You're done!

Formatting a Bootable Drive

Formatting a bootable drive is a little more complicated, because Windows doesn't allow you to format the drive or partition that is currently running. The trick is to format the disk while Windows is not using it. To begin, restart your computer and hold down the F8 key. When the Advanced Boot Options screen appears, choose the Repair your computer option, and press Enter. (If the "repair your computer" option is not present, you can also access it by booting from your Windows 7 Installation disc.) If you have more than one Windows installation on your computer, select the one that corresponds to the disk you want to format. Most likely, you have only one, and this step can be skipped.

When the System Recovery Options menu appears, click on the Command Prompt link. When the command prompt window appears, you should verify that you're formatting the correct disk by first entering DIR C: at the command prompt. You should see something like this in response:

Volume in Drive C is TI105847W0F

06/15/2011 11:07 AM DIR Program Files
11/25/2011 03:46 AM DIR Users
02/25/2011 01:07 AM DIR Windows

If the DIR command shows that a Windows directory is present, you're in the right place. Here are the command options to reformat drive C:

  • FORMAT C: /fs:NTFS (Do a long format, which will scan for bad sectors)

  • FORMAT C: /q /fs:NTFS (Do a "quick format" which does not scan for bad sectors)

  • FORMAT C: /p:2 /fs:NTFS (Format and write zeroes to every sector)

In most cases, the first command is the one you should use. Add the /q option only if you're in a hurry and you're reasonably sure there are no bad sectors on the drive. The /p:2 or /p:3 option can be used if you want to make sure all the data on the disk is wiped and replaced with zeroes.

If you have drives other than C: and you want to format one of those, change C: to the desired drive letter. The format command may ask you for the volume label of the drive you are formatting. Enter the volume label shown in the DIR command, then press Enter. Format will give you one final chance to change your mind, displaying a message like this:

CAUTION: All data on non-removable disk drive C: will be lost!
Proceed with Format (Y/N)?

After you reply with Y at the prompt, the formatting will begin. A long format on a large drive can take hours, so be prepared. When formatting is complete, you'll be prompted to enter a Volume label. This can be the same label as before, or any string of 11 characters. After formatting, you will need to restart your computer. If you just formatted the bootable partition, you'll need to start with the Windows 7 Install disc in the drive, so you can reinstall the operating system.

Do you have something to say about formatting a hard drive with Windows 7? Post your comment or question below...

Ask Your Computer or Internet Question

  (Enter your question in the box above.)

It's Guaranteed to Make You Smarter...

AskBob Updates: Boost your Internet IQ & solve computer problems.
Get your FREE Subscription!


Check out other articles in this category:

Link to this article from your site or blog. Just copy and paste from this box:

This article was posted by on 28 Mar 2011

For Fun: Buy Bob a Snickers.

Prev Article:
Windows 8 Preview

The Top Twenty
Next Article:
Installing a Wireless Router

Most recent comments on "Reformat Windows 7 Hard Drive"

Posted by:

28 Mar 2011

I'm using a 4GB.USB flash drive for ready boost in Win7 formated in NTFS would it be better to use FAT32 as you say in #1 ? thanks :)

EDITOR'S NOTE: Sorry, I meant to say that FAT16 is generally best for USB drives. But I don't know if a FAT16/NTFS test has been done in a ReadyBoost context. Try it and see!

Posted by:

29 Mar 2011

Can I add a new drive, format it, add the operating system (Windows 7) and them swap it with the existing C: drive? Performing a backup and then wiping out the drive, only to reload files seems like a miserable task. New drives are bigger, faster and reasonably priced. Once I have the new drive installed the old drive can be cleaned up and used as needed.

EDITOR'S NOTE: Yes, you want to clone your drive. See

Posted by:

03 Aug 2011

Did I miss the "printer friendly" link?

EDITOR'S NOTE: Yes, it's right before the "Check out other articles in this category" heading.

Posted by:

23 Jan 2012

I am replacing a HDD with a 128GB SSD. How do I partition the ssd for the OS , and how large should it be for win 7 pro 64 bit ? Is there a benefit to placing the os in a partition

EDITOR'S NOTE: There is no requirement (or need) for partitions, unless you want to have a multi-boot system. Some argue for a separate partition for the OS, and another for data. But my advice has always been "keep it simple" with a single partition.

Posted by:

Bob Evans
12 Aug 2012

I followed your suggestions on fixing Windows 7 problems and "Repairing your computer" and using the System Recovery Tools. No luck. So I then went to your article "Reformat WIndows 7 Hard Drive". I managed to rediscover the "CD C:/" command and I got to the point of entering the "FORMAT C: /fs:NTFS" commend. When I said "yes" to the "Format?" question, I received the following: "Format cannot run because the volume is in use by another process. Format may run if this volume is dismounted first. All open handles to the volume would then be invalid - would you like to force the dismount of this volume?" I replied "yes". I then got the following message: "Cannot lock the drive. This volume is still in use." So, where do I go from here???

Posted by:

Md.Abid Hasan
19 Mar 2013


System Partition is not allowed to be formatted.

Posted by:

Freddy Salazar
21 May 2013

I followed what you suggested and I got a "cannot format this volume is write protected". I just want to wipe everything clean and do a clean install. My computer only boots from windows 7 dvd because I lost power during the original install. Now I only see one partition instead of three and that one doesn't say primary it says lodgical. Please help I might have messed my netbook up more then fixed it. Thankyou

Posted by:

Jack McNac
24 Jan 2014

Since formatting a large USB drive will take hours, is it safe, in Windows 7, to close the disk management thing and use the computer for other tasks while the format runs in the background? Is it OK to log off the admin account and log in as an ordinary user to use the computer while the formatting runs? Or should I leave the admin logged in and just switch to my regular user account if I want to use the computer while the formatting runs? Also, my Windows 8.1 machine cannot see the Windows 7 machine on the LAN while the format is running. Is this because the Win 7 machine is formatting the drive, and that makes the entire machine invisible to the LAN? Or is it just Windows 8.1 being its usual buggy self?

Post your Comments, Questions or Suggestions

*     *     (* = Required field)

    (Your email address will not be published)
(you may use HTML tags for style)

YES... spelling, punctuation, grammar and proper use of UPPER/lower case are important! Comments of a political nature are discouraged. Please limit your remarks to 3-4 paragraphs. If you want to see your comment posted, pay attention to these items.

All comments are reviewed, and may be edited or removed at the discretion of the moderator.

NOTE: Please, post comments on this article ONLY.
If you want to ask a question click here.

Free Tech Support -- Ask Bob Rankin
Subscribe to AskBobRankin Updates: Free Newsletter

Copyright © 2005 - Bob Rankin - All Rights Reserved
About Us     Privacy Policy     RSS/XML

Article information: AskBobRankin -- Reformat Windows 7 Hard Drive (Posted: 28 Mar 2011)
Copyright © 2005 - Bob Rankin - All Rights Reserved