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Make a Bootable External Hard Drive and Install Windows 7/8

Step 1: Format the Drive
Just place the flash drive in the USB port of your computer. Open command prompt (cmd). You can do that by pressing WINKEY+R, right click on the listed file and click on “Run as administrator“.
Enter the following commands in the same order as I did here:

list disk
select disk z (where z is the number corresponding for your USB disk. You have to replace it with the corresponding letter from your own system).
create partition primary
format fs=fat32 quick

Diskpart Bootable USB

Please be careful using the select command (so you don’t select and format your hard disk instead)

Diskpart External Hard Disk

If everything goes well, this is how your cmd screen will look like

Step 2: Mount The Windows 8 ISO Image Into A Virtual Drive

If you don’t have a physical optical drive you should mount the image into a virtual drive. You can install and use PowerISO

Step 3: Make The External Hard Disk Bootable

I’m assuming that F is your drive letter with Windows 8 ISO image and G: is the location of your external hard disk (or flash drive) . Open the command prompt screen (as administrator) and type the commands:

cd boot
bootsect.exe /nt60 g:

External Hard Disk Bootable

Also, don’t forget to triple check the target location so you don’t accidentally delete the boot sector of your hard disk

Step 4: Copy The Installer Files

After the above step, don’t close the command prompt (at least not yet). At this moment your new external hard disk or flash drive is bootable but you need to execute one more command in order to transfer the files to your new drive. You have to type the following command line:

xcopy f:\*.* g: /e /f /h

Again replace the drive letters with the ones that apply to you. Alternatively you can copy all the files in the virtual drive to the flash drive or external hard drive by using Windows Explorer, but using XCOPY ensures that system and hidden files are also copied.

Step 5: Boot Off The External Hard Drive or USB Flash Drive

To use and boot from your newly created drive on your netbook or computer, first you have to set your computer you must set it to boot through the USB flash drive. In order to do this shut down your computer, go in the CMOS setup by pressing the “DEL” or “F2″ key when the computer power on, without unplug the newly created external hard drive or USB Flash Drive from the machine. Set the device as the primary boot option, save the changes BIOS and restart. On newer computers you can boot from the device without entering into BIOS by pressing either “ESC”, “F9″ or “F11″ (different key on different manufacturers).

External Hard Drive bootable

Now you can install Windows as usual. Please be aware that if you’ve changed the boot sequence in the BIOS, remember to change it back as it was after copying the files (usually after first automatic reboot).



  1. After following these instructions to a T, I booted the eSATA external drive. It displayed “Verifying DMI Pool Data” and just hangs.

    The problem could be that I used Windows XP diskpart. It does not have format as an option. I had to use the “format” command. This still did work and I could open, read and write to the external drive. I copied the Windows 7 install files to the external.

    The BIOS is set to boot only from the external drive, but It just won’t boot.

  2. PowerISO x64 installer keeps triggering multiple antivirus alerts. The installer is trying to install Medisunu.exe, which Heur.AdvML.B nested in it. This is not a good method due to serious security risks.

    • It’s not a good method due to multiple security risks…like your downloading software off the Internet and installing it on your computer as an administrator? LOL

      What exactly is a good “secure” method to copy a drive into an ISO on your computer, in your estimation? If you’re going to condemn this method without supplying a better (ideally effective and secure) one, then what use are you?

  3. hello sir
    i want to install windows xp 2007 through bootable usb

  4. Getting just a – when starting up. Any idea why this is happening? Previously, was giving me an error that no operating system was found.

    • Same issue, would like to know what’s wrong.

  5. Wow I am so happy, It work, I love u guy tnx

  6. Hi, my diskpart says “the volume size is too big”
    I am only only using a 80g as test
    any help would be greatly appreciated

    • Same issue

    • Use
      =ntfs quick
      Instead of fat32

    • Quick format in Fat32 have limitation (less than 32gb).

      I used the software PartitionGuru to quick format in Fat32, very easy.

      Hope it helps.

  7. Can someone break down what [part of] the “xcopy” line means? I’m curious what the two stars represent (“*.*”) as well as “/e /f /h”.

    • * represents any string (basically any ordered group of letters and numbers). *.* tells the computer to run the command on all files names of all file types (for instance readme.txt, sys18.bin, goatse.jpg: since readme, txt, sys18, bin, goatse, and jpg are all strings, the machine will run the operation on them. The e, f,h are all options that effect the behavior of the command in this case xcopy (e copies empty directories, f displays filepath and, h copies hidden files/folders).

    • You can type “help xcopy” and it’ll tell you what those extra letters and commands mean.

  8. format fs=ntfs quick I got an error message. 0 percent completed. Virtual Disk Service error:The volume is not online

  9. Everything works right up until its time to actually install Windows from the newly created external USB drive, at which point Windows 7 says that it does not support booting from an external USB drive.

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  11. Nice & detailed tutorial to make external HDD bootable but there are few small softwares too which can make flash drive or HDD bootable with just few clicks e.g. rufus, universal usb installer.

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  13. Could not map drive partitions to the associated volume device objects:
    Access is denied.

    • You have to run cmd as administrator.

  14. G:\boot>bootsect.exe /nt60 e:
    Target volumes will be updated with BOOTMGR compatible bootcode.

    Could not map drive partitions to the associated volume device objects:
    Access is denied.

    • You have to run cmd as administrator

  15. I will not sap Make a Bootable External Hard Drive and Install Windows 7/8 – Bootable USB | Bootable USB

  16. In some cases of a large external drive you may need to use :

    format fs=exfat quick

  17. you guys start recognizing the differance between boot as start the computer to work OR fresh INSTALL !!
    MS is a leading culprit to this confusion .
    even the comments here and some let them self mix the word bootable and fresh and new install.

  18. Excelent, thanks, he helped me solve the problem with my flash drive.

  19. Hello,I log on to your blogs named “Make a Bootable External Hard Drive and Install Windows 7/8 – Bootable USB | Bootable USB” daily.Your story-telling style is awesome, keep doing what you’re doing! And you can look our website about love spells.

  20. Worked as magic.
    Thank you very very much.

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