My USB drive used to be originally 8GB when I bought it.

I'm trying to reformatted in Windows 7 by right clicking on the drive and selecting Format.... But the capacity only shows 250MB.

Is there something I can do to get the original size back? Maybe it got partitioned in a weird way?

The flash drive is a SanDisk Cruzer Micro 8GB. I got it from Wal-Mart but this is the same drive. http://www.amazon.com/SanDisk-Cruzer-Micro-Flash-SDCZ6-8192-A11/dp/B000UZN2ZK


9 Answers 9


You should try BootIce. BootIce is a portable, free utility designed to directly customize and fix drives at a deep level. It is able to edit, restore, install and backup MBR, PBR, partitions and sectors of drives.

CAUTION: Because of its powerful capabilities, using this program can render your drive non-functional. There is no Reverse option to recover from changes made through use of this utility. Always use caution when using BootIce and make sure you know what you're going to do is the way to what you want to accomplish before attempting to make use of its functions.

As I happen to have a flashdrive with this same problem, I'll add a walkthrough below with the precise steps on how to fix it. But first, a bird's eye view of the problem in My Computer:

Bad flashdrive in my Computer

Compare that to the results in DiskPart:

Bad flashdrive in DiskPart

The drive's original size is 32GB, however incorrectly shows as only 242MB. To correct this, proceed as follows:

How to recover a flashdrive's full capacity using BootIce

  1. Download BootIce, bot x64 and x86 versions are available from softpedia.com:


  1. Extract the .rar file into a location of your choice. As BootIce is a portable program, you can run it from flashdrive or external HD.

  2. Verify the drive you have is the one with the problem. ATTN: Deleting partitions will erase all data. Make sure you back up any important files or data you do not want to lose before proceeding.

  3. Insert the verified USB with the issue into your computer's USB port.

  4. You will need Administrator access to run BootIce as it requires formatting priviledges. Right click BootIce and select Run as Administrator.

Run BootIce as Administrator

  1. Select the destination drive from the dropdown menu and click the Parts Manage button.

BootIce main screen

  1. A new screen will open, with the drive and any partitions beneath. Here you can modify parameters, such as partition sizes and Windows assigned drive letter. Select the main drive, the first option on the list and click the Re-Partitioning button.

BootIce partition management window

  1. In the popup window, select the single partition or multi-partition option depending on the partition(s) of the drive. In this example, we'll select the Single Partition option to restore the full usable size to the drive. Below, select the type of File System best matching with your drive, either FAT16 or FAT32 for flashdrives. This one is FAT 32. You may assign a name for your flashdrive in the Volume Label box. Leave all other options as default. Click OK.

BootIce formatting popup screen

  1. A confirmation box will appear, to proceed if you are certain click OK. NOTE Pressing OK will reformat the drive and delete all data. If your drive contains data you don't want to lose, select Cancel and do a data backup.

BootIce comfirmation box

  1. The popup window will gray out during processing and progress will be displayed in the titlebar.

BootIce formatting in progress

  1. If all goes successfully, when finished you should see a confirmation pop up appear.

BootIce confirmation of completion.

  1. You should now see the correct drive size appear in My Computer.

Successfully formatted flash drive in My Computer

Congratulations, your drive is now ready for use!

enter image description here

  • An Anonymous User suggests: It Is Better To Use .. HP Usb Disk storage Format Tool And .. Use It.... .. Step : 1 Download HP Usb Disk Storage Format Tool On Google. 2. Run As A Administrator In Case Windows 7 and 8 3. Go To The Device : Select Pen Drive Letter .. Which You Wants To Format. 4. File System : NTFS OR FAT32 5. If You Want Quick Format .. So Push or Click On Start Button... If You Wants Full Low Level Format . Then ... Un Check Quick Format Level..... 6. Wait For Process 7. Your Lost Storage Capacity Gain 8. Enjoy !!!
    – Psycogeek
    Sep 1, 2013 at 20:02
  • In case you still want to use the BOOICE app (it worked great for me) here pendriveapps.com/bootice-partition-flash-drive-edit-boot-sector is a link with current info about it along with author's website and download link for the app itself. May 21, 2014 at 8:20

The command line procedure is not simple, but it is the most likely thing to work.

When re-formatting the "drive" you're actually only formatting a partition on the drive. You need to use the diskpart utility to remove the partitions and create 1 single partition covering the full volume.

diskpart can be a bit dangerous, because if you pick the wrong disk or partition, you can remove data or partitions that are extremely, EXTREMELY important and lose all data on your machine.

Proceed with extreme caution!

Open up a command prompt as administrator (open the start menu, type cmd and press Enter.)

Type diskpart and press Enter. You'll end up with a new prompt that looks like this:



list disk <ENTER>

and you'll get a listing of all drives on your machine.


select disk # <ENTER>

to select a disk, where # is the number of the disk Windows screw-balled. Usually, the device is disk 1, but it's always best to make sure.

Then type

list partition <ENTER>

to get a listing of all partitions on the disk.

If you're sure you have the right disk/partition, you can then repeat typing

select partition # <ENTER>
delete partition <ENTER>

until all partitions are removed from that drive (you may need to type delete partition override for protected partitions).

Once the drive is empty, exit diskpart and remove the drive. Wait at least 5 minutes, then re-insert the drive. DO NOT CLICK FORMAT – this will most likely re-create the problem. Instead, enter diskpart again, and select the disk. Then type

create partition primary <ENTER>

Once you have created the partition, exit diskpart and, in the command promt, type

diskmgmt.msc <ENTER>

This will provide a reliable way to create a FAT32 partition. On the drive you would like to format (NEVER TOUCH DISK 0!), right click and select format. The allocation unit size option should be default, and the File System option should be set to FAT32. The format may take a while, depending on the disk size, be patient.

This should fix partition troubles on any readable USB flash drive.

  • 10
    This is a really good answer. I've always prefer to do all by my self not with third-party tools that i do not have control of. Thanks.
    – mnmnc
    Nov 5, 2013 at 15:27
  • 10
    Why we should wait for 5 minutes?
    – frogatto
    Jun 17, 2014 at 9:11
  • 1
    Didn't wait, my house wasn't set on fire. Other than that, thanks, it worked! Nov 24, 2015 at 21:50
  • 7
    Note: you may need to type delete partition override for protected parititions Jan 15, 2016 at 9:11
  • 3
    This worked even without closing and restarting diskpart. I successfully created the partition in diskmgmt after just deleting partitions. Jan 15, 2016 at 9:11

When re-formatting the "drive" you're actually only formatting a partition on the drive. You need to use the diskpart utility to remove the partitions and create 1 single partition covering the full volume.

diskpart can be a bit dangerous, because if you pick the wrong disk or partition, you can remove partitions/disks/etc. that you didn't want to remove, and lose all data on your machine. Proceed with extreme caution!

  1. Open up a command prompt as administrator (open the Start menu, search for "Command Prompt", right-click and select "Run As Administrator". You'll get a black text-only window that pops up.

  2. Type diskpart and press Enter. You'll end up with a new prompt that looks like this:

  3. Type list disk, and you'll get a listing of all drives on your machine.

  4. Type select disk # to select a disk, where # is the number of the disk you want to edit.

  5. Then type list partition to get a listing of all partitions on the disk.

  6. If you're sure you have the right disk/partition, you can then type select partition # and delete partition until all partitions are removed from that drive.

  7. Once they're all removed, type create partition primary to create a new partition that covers the entire drive. Alternatively, at this point you can create multiple primary partitions of varying sizes as needed by appending SIZE=# (in MB) to the end of the create partition statement. Not specifying a size will use the entire disk.

  8. Once the partition is created, type exit twice (to exit diskpart, and then to close the command prompt) and then use the format option to format that blank partition.

  • 3
    You can just do this from the Disk Management console if you'd rather not fight with a command line. It's safer for the uninitiated.
    – Shinrai
    Jan 25, 2012 at 15:22
  • 2
    I'm a command-line junky... I admit. That... and sometimes the windows disk-management utility won't allow you to do some things.
    – TheCompWiz
    Jan 25, 2012 at 15:24
  • 2
    @Shinrai Sadly, the Disk Management Console doesn't let you mess with partitions on thumb-drives. It is hard-coded to only allow 1 partition on removable storage.
    – TheCompWiz
    Jul 10, 2013 at 13:10
  • ... but then again... Windows doesn't understand multiple partitions on a single removable drive either...
    – TheCompWiz
    Jul 10, 2013 at 13:11
  • 1
    On step 6: If select partition ### responds with There is no partition selected. even though the partition number exists, the partition may be corrupt. In this case, to clear out the partition, you will need to (cautiously!) enter clean -- this should reset all partitions.
    – Jonathan
    Nov 18, 2015 at 23:45

Use this empty bootsector program if you want to reformat your device when you have written multiple partitions on you flash drive and Windows doesn’t recognize the full device size anymore. Just restore it in device mode

  • 2
    Most straight forward solution. The court answer does not explicitly state that you need to use a tool that writes the image into the USB drive. You can use the USB Image Tool that can downloaded from that page, or Win32DiskImager is a popular choice. Jan 1, 2016 at 15:18

If something is wrong with the partitions then you need to change them.

  • Open your startmenu and search for diskmgmt.msc to open the partition manager,
  • Select the usb device
  • Delete all the partitions you don't want (preferably the ones from your usb drive),
  • Create one big partition (if you want to use it on other operating systems choose exFat or FAT32),
  • Format the new partition.
  • 3
    Under some circumstances (I'm not sure what they are) the option to delete the primary partition is missing. I had to use BootIce as per @thane's answer to wipe all partitions
    – Basic
    Nov 8, 2012 at 2:10
  • These instructions may work for normal hard drives, but I do not think they work for drives that Windows detects as removable. Feb 27, 2013 at 22:34
  • In my case, the option of deleting was also missing, so I chose to apply @DerekHatesMicrosoft.'s option. Dec 15, 2014 at 15:04
  • Wow so simple compared to other answers. It worked! Jan 19, 2016 at 17:57

There appears to be a problem these days with fake flash drives ( google: flash drive scam ). In many cases, the drive has been altered to report a higher amount of storage than is really there, and if you attempt to use it, you will wind up with lost data.

See for instance: ( http://sushifury.com/2010/03/i-got-sold-a-fake-usb-flash-drive-on-ebay-heres-how-i-fixed-my-situation-and-how-you-can-avoid-this-situation-yourself/ )

If you got it for a really good price, consider examining your flash drive more carefully.

  • 3
    I purchased it from Wal-Mart and I was able to burn a 4GB operating system on it once that worked. I doubt it's fake but thanks for the warning.
    – fent
    Jan 25, 2012 at 22:24
  • 1
    In case that link goes down, the testing program is H2testw, and it's worth running on new drives even if you think it's good - if nothing else, it'll tell you the speed of the drive and verify there's nothing wrong with it.
    – Bob
    Nov 17, 2012 at 7:48

I've added my own answer to this because the current best answer is a long-winded graphical solution, and the only other command-line solutions are longer than they need to be or leave whole stages of the process to be completed in the GUI. This is currently the only pure command-line solution, and I like to think it's also a pretty simple one.

Restoring the Drive to Its Original Size

Start by opening CMD as an Administrator (open the Start menu, type CMD, right-click and select "Run as Administrator").



...to start Windows' command-line disk partitioning utility.

Next, type:

list disk

...to list all available hard-drives. Compare the sizes of the listed drives, and when you're certain you have the right one, type:

select disk #

...where # is the number of the drive that you want to select.

This is the first major difference to the other command-line solutions given to this question - listing, selecting and then deleting individual partitions is cumbersome, and when the purpose is to remove all partitions, it makes much more sense to use clean, which does the exact same job and does it quicker.

To remove all partitions from the selected disk, type:


...and wait for the process to finish.

Finally, type:

create partition primary

...to create a single partition covering the entire disk - this is the "default" configuration, suitable for most purposes. You can repeat this step to create as many partitions as you'd like. Remember that an MBR disk can contain a maximum of four primary partitions*.

Once a primary partition has been created, the drive should be back to its original size.

Formatting and Initialising the Drive

Having restored the drive to its original size, you'll still need to format it with a file system to make it usable. This is where the other answers either stop short or delve into the GUI, but this part of the process can just as easily be done from within the command-line, and it makes little sense to go most of the way via the CLI and then use the GUI only to format the drive... especially when the command-line feels way cooler.

To format the disk, type:

format quick fs=fat32

...replacing fat32 with the file system you want to format the disk with. Use fat32 for a disk that will be compatible with the most amount of systems (including media players, Kodi boxes, Android boxes, etc.), or ntfs if you need to support individual file sizes larger than 4GB.

Finally, type:


...to assign your newly-formatted disk a drive letter, making it visible to Windows.

Your necessary disclaimer that diskpart is a disk-claimer. The command line is dangerous, we all know this, etc., etc. However, nowhere is this more true than within diskpart, where a drive's number can change at any given time for a multitude of reasons, which means it can take entering a single mistaken digit for you to kiss goodbye to all the data you have on your drive. I cannot emphasise this point enough, having just spent the better part of a week trying to recover a disk I'd accidentally set diskpart on after running it for what must have been the umpteenth time in a night. The command-line is a beautiful, powerful tool, but with that power comes danger. Use it with caution, and coffee in your bloodstream.


My usb drive only showed as about 20 mb in size after using it to make a bootable linux drive.

I successfully used a tool called SD Formatter 4.0 to format it with the actual size. Have a look here Restore Your USB Key to it's original state

After having tooled around with a USB Linux version using your image overwritten or multi partitioned flash pen drive, you might find it necessary to revert it back to a single fat partition (restore the flash pen drive to it's original state) that can again be read by all computers. Windows users can follow the Windows instructions below to Restore a Flash Drive using the HP USB Format Tool. For those working from Linux this task can easily be accomplished via the Linux Flash Drive Restoration tutorial that follows.


Did you try the HP USB FORMAT UTILITY, if this can't format it right, then it's bad, download here:


  • What makes this one better than formatting with the built-in tools, or the third-party tools previously mentioned? Rather than building a list of all available similar tools, which can be done with a Google search, it's better to describe what makes this a good solution. Good guidance on recommending software here.
    – fixer1234
    May 16, 2018 at 7:07

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