How To Install Windows 7 To USB External Hard Drive [Must Read]

As you likely know, while one can install Windows 7 from an external hard drive, one can’t install the same to an external hard drive with default settings. For all those users waiting for a good workaround to install Vista, Windows 7 and Windows Server 2008 R2 to an external hard drive, here is the complete solution.

Windows 7 SP1

Even though Windows recognizes and displays the USB hard drive in the installation screen, it doesn’t allow you install Windows on the same. When you attempt to install Windows 7 on external drive, you get “Windows cannot be installed to this disk” error.

Install Windows 7 to an USB external hard drive

So, if you want to install Windows 7 on an external hard drive you need to follow the steps given below. The procedure is simple but you need to install Windows Automated Installation Kit (WAIK) first to get some files. We would like to thank fujianabc @ boot-land forum for this workaround.


# An external hard drive formatted with NTFS

# Windows 7 installation files (if you have Windows 7 ISO use Virtual Clone Drive freeware to mount it)

# Windows Automated Installation Kit (free download from Microsoft)

NOTE: Make sure that you have a minimum of 15 GB free space on your external hard drive before starting the procedure. Although we are not going to delete the contents of external hard drive, we recommend backing up your external hard drive contents before trying this guide.


Step 1. Create two folders named Windows Files and WAIK Files on your desktop or any other drive which has a minimum of 5 GB free space.

install windows 7 to an usb external hard drive

Step 2: Download the ZIP file from here and extract the contents to WAIK Files folder. Before starting the actual installation procedure, you need to have three files: Bcdboot.exe, Bootsect.exe and Imgex.exe. These files can only be obtained by installing Windows Automated Installation Kit for Windows 7 on your Windows PC. After installing WAIK, simply search for these files in the Windows installation drive to get them. Once you have these three files, copy them to WAIK Files folder that you have created in the above step.

Install Windows 7 to an USB external hard drive10

Step 3: Copy all the contents of Windows 7 installation DVD to the Windows Files folder.

Step 4: The next step is to run Installer.cmd file as Administrator (Right-click on installer.cmd and select run as administrator). In the first screen, you will be asked to press Enter to continue.

Install Windows 7 to an USB external hard drive15

Step 5: Press Enter key to browse to the install.wim file present in the Windows Files folder. The Install.wim file can be found under Sources folder (Windows Files/ Sources/ install.wim).

Install Windows 7 to USB external hard drive1

install windows 7 to usb hard drive

Step 6: Now, you need to select the Windows 7 edition that you want to install on external hard drive. You can select the edition by entering the index number shown in the screen. For example, type “5” (without quote) and hit Enter key to select Ultimate edition.

Install Windows 7 to an USB external hard drive2

Step 7: The next step is to enter your External drive’s drive letter. Enter the drive letter (ex: L) and press Enter key.

Install Windows 7 to an USB external hard drive3

Step 8: Now, type in the drive letter of your ACTIVE partition and hit Enter key. Generally “C” is the active partition. You can find the active partition by opening Windows Disk Management tool (type diskmgmt.msc in Start menu search area and hit enter to launch it).

Install Windows 7 to an USB external hard drive4

install windows 7 to usb external disk

Step 9: Finally, the installer will ask you the drive letter that you have entered to install Windows 7 is a USB hard drive or not. As you are installing Windows 7 to an external hard drive simply type “Y” without quote and press Enter key.

Install Windows 7 to an USB external hard drive5

Finally click Enter key again to start extracting the Install.wim files. This might take a few minutes. Once done, you will be asked to reboot your PC to continue the normal Windows 7 installation procedure.

Install Windows 7 to an USB external hard drive7

Install Windows 7 to an USB external hard drive9

Step 10: Reboot your PC and follow the usual Windows 7 installation procedure to complete Windows 7 installation on external hard drive. Your PC will be restarted twice or thrice during installation.

Please note that the installation procedure might be slower as you are installing Windows 7 to an external hard drive.

Step 11: Once done with the installation, you are good to go. You can install all drivers and other software to start using the best Windows version on your PC.

Note: We have tested this method to install x86 flavor of Windows 7 to Seagate USB external hard drive. But should work fine with x64 as well. Users who would like to carry Windows 7 on a USB flash drive can follow our how to carry Windows 7 on USB flash drive guide.

UPDATE: If you’re having issues with this guide. please go through our how to install Windows 7 on USB with ease guide for easy instructions.


  1. User says

    One of my biggest frustrations with the Net is people who actually know less than they want people to think they do. I am wanting to put Windows 7 Pro 64-bit on a stick, and i am doing some reading to see how to do it. I just wasted some valuable time reading this crap. One good soul at least warned us that using this method can damage our C drive installation of Windows as well! Flush this stuff down the sewer and give us GOOD instructions on how to create a bootable Window USB drive.

  2. says

    Hi i followed the instructions and successfully installed Windows 7 on an External Hard Drive.However after Windows was installed when i tried installing other programs i kept getting File System Corrupt messages.Went through CHDSK and even then kept getting File System Corrupt, couldn’t even complete sfc completely.All told i spent more than 2 hours and my C Drive on External Drive is useless except for booting up Windows 7.Waste of my time.Now I’ll just Format it and Install Windows the normal way.Thanks for wasting my time!

  3. admin says

    This guide was originally written back in 2010. There were no easy-to-use tools back then.

  4. Frank T says

    What I don’t understand is, why this long way, when you can use the “how to install Windows 7 on USB with ease guide” is there other benefits of it ?
    But cool the easy way is there …


  5. ionut says

    You’d better use WinToUsb 2.0 beta. It works fine and it’s free. You’ll need windows 7 installation dvd in iso format.

  6. ashish says

    it works fine on my laptop .. but when i am booting my external hdd from another laptop(with a crashed internal hdd) it shows an error “bootmgr is missing” after i hit ctrl+alt+del system reboots and shows an error “no bootsector in usb device”

    please help me

  7. Lubomir says

    dear friend, why do you make a fool of all of us? Nothing works by your procedure.
    Only result is blue screen.

  8. Jon says

    yep tried it and I must be missing something because it showed a blue screen after the first reboot to finish install.???
    Anybody get passed this? Thanks

  9. demz says

    I just want to warn you guys, these instructions will mess the OS which is installed in your internal HDD and will corrupt your system files. This article is invalid.

  10. Misbah says

    I tried to install windows 7 on my external hdd using dell laptop running windows 8. Everything worked fine till i restated my pc. Now my screen is stuck at windows boot manager where a file ‘winload.exe’ is missing and corrupt. I cant go onwards as my original windows 8 is not listed in the OS options. Only windows 7 is here which is not loading correctly. Please help. I am in a mess :(‘

  11. Mack says

    When I run the installer it tells me I need 521 my of free space on any partition for temp files to install Windows. Free enough space and restart installation.

    Error code 0x80070103

    I have gigabites of free space on any number of partitions including my primary active.

  12. Taylor M. says

    So I have a question which may seem dumb, but I’d rather be safe than sorry. My mom’s laptop is broken and I suspect its the hard drive. I’d like to install windows 7 onto an external hard drive and run the laptop from said drive. I just want to make certain that I won’t change anything on MY windows 8.1 computer when I use my computer to install the windows 7 operating system onto the external HD.

  13. martin says

    Hi all,
    Im trying to install windows 7 on my external HDD. Im in point to reboot the pc, i have set the bios boot from usb but it will is working only to point where the WINDOWS logo is shown for a few seconds and after this whole pc get an bluescreen. What i’m doing wrong ? I have tried to reinstall the windows on HDD several times but still the same issue. :( getting tired of this. If someone can help i will appreciate it ! thank you :)

  14. Justin says

    This process works great for Windows 7 but installing with Windows 7 SP1 ISO or after installing updates through Windows Update causes your installation to blue screen. However, if you do not install any of the Windows 7 updates, this will work great.

    @dinescu : the install.wim should be at this path: Windows Files/ Sources/ install.wim after you copied your Windows 7 installation files like in step three above.

  15. Brian says

    The installer cannot find install.wim. When I hit enter to search nor if I manually type path…please help!!!

  16. Dinescu says

    yeah it works…….but I’m guessing that for most people after reboot it’s not an automatic spoon-fed menu installation……’s manual and involves using Windows SIM which appears in the start menu after you reboot……there’s instructions on what to do on the web if you search it…’s not hard, just really freaking tedious.

  17. Dinescu says

    the same thing that happened with everyone else who commented here; works fine up until you reboot to finish installation. at first I thought this was because I installed the iso image into a ntsf formatted partition on the external hard drive and it had to be FAT32 or exFAT because another blog this author wrote stated something like “in order to boot windows from usb you have to use UEFI and not Legacy” (which I’m assuming is the default for most machines?) but then when you reformat the external hard drive where you want install windows as exFAT or FAT32 the “fast installer” gives you the message “disk is not ntsf format, reformat disk to ntfs”.

    I’ve yet to try to install the windows iso to a FAT32 flash drive using “live linux” or “universal iso to usb” or “linux multibooter” applications (all free, all online for download) with the computer in UEFI secure boot mode; it doesn’t work in Legacy mode, or least hasn’t for me yet (and I tried on two different laptops. It must work though because why would linux guys include an option on their pendrive-writing programs for windows 7, 8, pro, etc if it didn’t work? wouldn’t make sense.)

    You can use this method to install a new clean version of windows in place of the one you have; all your data, settings, drivers and software are erased though so if you want you want to keep them you have to back them up beforehand. to do this you input the same disk for both the Active partition and the installation partition.

  18. Ethan F says

    Hi guys

    I used easyBCD and f**** up and deleted my BOOTMGR system partition and now I’m in this mess like the rest of you!

    Luckily, I had saved ALL of my data (pictures, music, documents, etc.) in a separate partition so retrieving my data was super easy.

    I took out the 2.5” HDD from my laptop and used Fosmon Technology USB 2.0 to 2.5″ 3.5″ IDE SATA HDD Hard Drive Converter Adapter Cable + AC Power Adapter (it’s $9.95) to connect HDD to my asus netbook, and then I transferred all my data (107GB in 1 hr over usb 2.0).

    I then formatted the HDD completely and erased everything.

    I don’t have a flash drive now and the one I ordered will arrive in 2 days, so I hope that I can put Windows 8.1 on the USB flash drive and that the empty HDD inserted into the laptop will automatically be able to install the OS and everything will be fine (hopefully).

    Anyway, I hope you can all retrieve your precious data!
    Remember, always have two partitions: one for your system and one for your data.

  19. Technik says

    Hi, thank you for the effort.
    I want to try it but i noticed that those who ask for your help concerning there “BOOTMGR is missing.” problem don’t get any response? What does it mean?

  20. glen says

    this does not work. everything installed correctly, but once it told me to restart my computer what do I do then? I boot up the install disk still says I cant use a usb, try and hook it up on the computer I am going to be using it on and its missing the BOOTMGR and another g something file. really wish people wouldn’t put things like this online unless they worked.

  21. David Burgin says

    ATTN!!! BOOTMGR is missing solved!

    You must be able to get into recovery. After following the method above and you get bootmgr is missing you need to disconnect your old hard drive. Then when you do start up repair it will repair external drive and then will boot.

    I am using mt laptop right now with no internal hard drive. Just my newly installed external hard drive

  22. 4N0N says

    Yeah so when I load the install.wim, no images show up at all. I guess it doesn’t matter as this author isn’t doing jack **** to help anyone. Thanks for nothing.

  23. Saidou says

    I have a company HP Elitebook 8470p. Because I don’t have any privileges in Windows, I want to try this tutorial out.
    My question is as followed:

    (1) If I take out the internal drive and try above method, will it then create a separate MBR partition to boot?
    The problem is that booting from another drive/boot partition is locked by my company (tried it with Ubuntu).

    (2) I also don’t want to make changes to MBR partition of that internal drive so I won’t get in trouble with my employer :) When I re-add the internal drive will it then keep 2 separate MBR boot partitions or does it merge it?

    (3) My boot menu for the moment has folowing priorities: DVD-drive –> USB –> HDD
    So whenever the external drive is not connected it boots automatically from the internal drive, when USB-drive (Ubuntu) is inserted it boots from the USB drive. (no changes to internal MBR drive)

    Thanks for your help.

  24. Steve says

    I just noticed that it says “external hard drive” specifically. Does this method work on usb FLASH drives?

  25. Steve says

    I have the same problem as Archmaester. I get a “BOOTMGR is missing.” every time i try booting from usb. I tried repairing with a Windows 7 dvd (both automatic repair and manual from command lines) , nothing help.Anyone knows how to fix this?

  26. Richard Mangaliag says

    Please help i got this error message.

    [ 0%] Applying progress
    Error restoring image.

    A required privilege is not held by the client.

    The Wim file applied O.K.

    Processing the registry and usb boot watcher…

    Error occurred when loading the registry
    Press any key to exit..

  27. Archmaester says

    Did all the steps above without mistake …it took me 141 minutes to finish the procedure but after that i received an error “BOOTMGR is missing.” after restarting and booting in USB …

    How to Fix this? pls respond ASAP … my IDE Hard disk is dead 1 day ago and i need a temporary solution using this method …

  28. Jasmine says

    This tutorial does not work when you try to install Windows 7 on a hard drive using a computer with MacOSX, my computer couldn’t run installer.cmd

  29. Kyle says

    I am sorry to say that but your guide only worked for me until step 9. When the copy process was completed, I tried to reboot from the Install DVD, where I got the usual error (cannot install on USB …) and the try to reboot from the external HDD just gave me a flashing _ . So, what did I do wrong?

  30. Daniele says

    Thank you for this guide!
    I have two questions:
    1) Would it be possible to install Windows 7 on a SSD plugged into a USB docking station?
    2) After installing, is it possible to put the SSD inside the notebook and boot from there, or will there be disk-letter problems?

    Thank you in advance

  31. Martin Hidalgo says

    Thanks you very much, the system was installed perfect !!!… Easy to do with your instructions.

  32. Koray says

    Can I use windows7 installed external drive with different computers? This is a so important. If I can’t, it doesn’t make sense having windows7 on an external drive.

  33. admin says

    Thanks for your comment. It should work fine. I have tested it. Are you getting an error while attempting to boot?

  34. chris says

    Did all steps when I reboot didn’t go into windows 7 installation shows me 2 window 7 OS’s one works (internal HD) and the other does not (external HDD) states kernel debugger is missing or corrupted how do I fix this please help .I guess you cant since you just delete one of my comments

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