How to Boot Camp USB 3.0 External Hard Drive

In this tutorial I will show you how to install Windows 10 onto a USB hard drive. This can be used as a stand alone bootable windows instillation and if you have a mac a bootable Boot Camp instillation. You will need a Windows PC or virtual machine as well as a Mac if you are wanting to Boot Camp. Before we start, this has only been tested with a USB Hard Drive. This may not work with flash drives.


We are going to get all the tools together first.


  1. On your Mac open Boot Camp Assistant and uncheck Create a Windows 7 or later version install disk. Make sure Download the latest Windows support software from Apple. You will need a 4GB or higher usb drive to download it too.
  2. First you will need to download a Windows 10 ISO. You can do this by going here. Follow the steps to get your specific ISO you need.
  3. When that finishes downloading open the ISO and go to the sources Find the install.wim (If you do not find a install.wim and only find an install.esd follow this to convert the install.esd to an install.wim) and copy and paste it to your desktop. You can delete the ISO. It is no longer needed.

Switch to Windows. This can be a virtual machine or a physical Windows instillation. (I recommend a physical instillation. I had problems with my virtual machine when partitioning.)


  1. Move your wim onto your Windows Desktop and put it on the Desktop for now. We will move it later.


  1. Next you need a tool called imagex.exe. It is a command line tool. To get this you can just click here to download.
  2. Move the wim and imagex.exe onto your C Drive. If you don’t know what that means. Open up File Explorer(that little folder icon you use to get to your documents) and type C:/ into the address bar at the top. The reason we do this is to make it easier to navigate to them while we are in command prompt. You may need to provide administer permission to move them to the C Drive. If this happens press Continue for both.
  3. Plug in your external harddrive.
  4. Open Command Prompt as Administrator. To do this open the start menu and find command prompt and right click on it and click run as administrator.

The next few steps will all be commands in the command prompt. So type each step or copy paste and press enter.

  1. cd C:\ (make sure you do a backslash and not a forward slash backslash is above the enter/return key)
  2. diskpart
  3. list disk This will show you a list of the devices connected to your computer. Find your external hard drive. The easiest way is to find the size of it. Now note the Number next to Disk.
  4. select disk n (where n is the number you noted before.)
  5. clean (this will clean all the partitions of the external hard drive and erase everything)
  6. convert mbr (Master boot record is the partitioning format we will use.)
  7. create partition primary size=350 (This will make a 350MB partition that will be used for booting)
  8. format fs=fat32 quick (this formats the partition to fat32)
  9. active (this makes it bootable)
  10. assign letter=b (this assigns a letter to this partition. If you wish to use another letter swap it with where the b Just make sure note of which letter you used) If Windows gives a popup about a drive, just ignore it.
  11. create partition primary (this will make a partition that uses the rest of the drive.)
  12. format fs=ntfs quick (formats it to ntfs)
  13. assign letter=o (o as in operating system not the number 0. This like the last one we assigned can be changed as well.)
  14. exit (this will exit you from diskpart. Stay in the command prompt though)

This is the moment of truth. You will now deploy the install.wim to the external hard drive.

Before you use imagex make sure you are focused on the C:\ directory. Otherwise it will not be able to find the install.wim file.

cd C:\ (you should have done this in step 9 but just in case I wrote it a second time.)(make sure you do a backslash and not a forward slash backslash is above the enter/return key)

  1. imagex.exe /info C:\install.wim (this is to find the index number of the version you want to install.)
  2. imagex.exe /apply C:\install.wim 1 o: (replace the 1 with the index number you found in the last step.) Be patient this will take a while.
  3. o:\windows\system32\bcdboot o:\windows /f ALL /s b:

Once that finishes you are done on the Windows computer and can close the command prompt and eject and unplug the external hard drive from your Windows machine.

If this ends in an error and you are using Windows 7, it is because Windows 7 doesn’t support the /f ALL command.

For Windows 7 use this: o:\windows\system32\bcdboot o:\windows /s b:

  1. Turn off your Mac.
  2. Plug the external hard drive into your Mac.
  3. Power it on and hold the option
  4. Choose EFI boot when the boot options show up.
  5. Follow the install instructions to install Windows. (It may reboot a couple times during instillation. Make sure to press option at every boot and choose the efi boot to continue the instillation.)
  6. Once Windows is done installing and boots for the first time plug in your usb drive that has the Boot Camp drivers and open the usb and press the setup.exe and follow the install instructions.

If you did it right, you will now have a full Windows instillation on your usb hard drive. Happy Boot Camping!

  • Дима

    Can’t do 25 step. Error for some reason.

    • Make sure that your drive letters are correct. They may be different based on what you did in previous steps 18 and 21. The o is an O not a zero as well. The b is the letter for the smaller boot partition.

      • Дима

        I think this is because I’m doing that on Windows 7, which have older bcdboot tool. Actually I can’t understand what I have to do in this case.

        • Oh wow I’m so sorry I didn’t include the windows 7 command. It’s a little different. Let me find it quick and I’ll add it.

          • Дима

            I’ve tried some variants but no one works for me. Would be great if you command will work.

            • o:windowssystem32bcdboot o:windows /s b:

              I added a section showing this separate command. Windows 7 doesn’t support the /f ALL command. I hope this works for you. I do want to warn you though I never could get Windows 7 to boot properly on my MBPr Mid 2014. I haven’t tried it with other models though. Best of luck to you.

              • Дима

                Still nothing if I’m using W10 bcdboot tool under W7. It shows up an error modal that says something about “o:WindowsSystem32bcryptPrimimtives.dll is not developed to run under Windows”. Originally its in russian 🙂
                If I’m using W7 bcdboot tool to create efi boot partition it finishes with success but no effect on Macpro. I’m choosing EFI Boot disk at start up, then goes 10-12 seconds delay and Sierra is starting to boot.
                Now I think that the best way to finish is to install W10 via Parallels and run bcdboot tool on that.
                Anyway, thanks for helping me.

                • Yes that would probably be best.

                  • Дима

                    Well, I have to say that theoretically my Goodram Iridium Pro 240Gb (in Patriot Gauntlet USB3 case w/ UASP) not supported to install Windows externally. No luck with booting from fully working installation.

  • faraz

    hey there great article i couldnt help but notice that you have used convert mbr (master boot record) do we really need to use it I mean what is wrong with GPT
    also you have kept the file partition as fat32 instead of NTFS

    • Honestly it’s only worked for me using MBR it would be a whole other process using diskpart. If you have a better way of doing it, go ahead and do it.

      What do you mean I kept the file partition as fat32? Step 20 formats it as ntfs. The boot partition is fat32.

      • faraz

        oh man i may have garbled a few steps sorry man

        • It’s alright this process can be very confusing and took a long time to figure out. Just take it slowly when you are doing the diskpart section. And don’t be afraid to restart the diskpart section if it doesn’t work the first time. I’m not against GPT at all I actually prefer it. I just haven’t found a process for that yet for installing Windows on an external drive.

          • faraz

            hey man what you have done if it works is a great help to us students man we really need windows on external drive, apple literally rips us off in matters of storage

            • Thanks! That’s exactly why I did it. I was a student when I first got my MacBook Pro and with 128gb of storage, gaming on Windows sucks cause windows took like 60gb. I researched this for like 6 months. Failed more times than I can remember, and finally made a process. I really wanted to share it with others so they can get a cheap external drive and run it on that. Apple only officially supports installing with Bootcamp to thunderbolt drives which prices for those are outragous. I really hope it does help. Let me know if you have any other problems with it.

              • faraz

                fingers crossed man!
                if it does work I would really encourage you to make a video and share on youtube.
                Presently i am working on a usb drive i made using my old laptop hdd and a JMicron Tech Casing of which chances are slim if it doesnt I will use my Seagate controller that will definately work,
                hope for the best 70% done 🙂

                • I’ve been thinking about a video now that there is a want for it. I’ll go ahead and make one maybe tomorrow or this weekend. I now have a nice tripod so I could do the parts that can’t be screencasted. Thanks for the idea no input it helps a lot. I’ve used various USB hard drives and enclosures so hardware shouldn’t be a problem.

                  • faraz

                    if you need any help feel free to contact me

                    • Same to you. You can use my contact section if you need any specific help over email etc.

                    • Faraz

                      dude there is an error stating windows setup couldnot configure windows to run on this computers hardware
                      its a macbook pro retina 2015 model

                    • When you chose the boot device did you chose efi or windows?

                    • Faraz

                      moreover I restarted to see if it works but there was a another error Installation Failed please restart the installer 🙁

                    • Something went wrong with the install.wim when it was being imaged. Try the tutorial one more time and make sure that your install.wim is not corrupt and that the index you chose is correct. It may be different than what I had above.

                    • Faraz

                      hey Full disclosure:
                      Macbook pro retina 13 inch base model
                      macOS Seirra
                      Bootcamp 6.1
                      there was no option to check uncheck as it used to be in earlier versions I dont know why
                      so maybe my step 1 bypass screwed the entire process 🙁

                    • All you need the bootcamp USB for is the drivers and no need for the installer. It will still make one but don’t boot from it. Boot from the USB hard drive then plug in the bootcamp made USB drive after windows boots and press the setup.exe to install the bootcamp drivers.

                    • Faraz

                      alright man I am restarting the entire process once again and this time I will use the Seagate Controller to avoid any further complications

                    • Alright let me know how it goes. If it doesn’t work I’ll make the video soon to clear up any confusion.

                    • Faraz

                      sure man this time I made a minute change
                      chose index to 2 windows 10 home isted of 1 windows 10 pro
                      and the seagate controller is fast compared to the JMicron one
                      These chinese are always looking to connect a few wires to make things work no quality!!

                    • Totally agree some enclosures are awefully made.

                    • Faraz

                      fingers crossed man
                      In the “getting ready” section of windows

                    • Oh you should be good then.

                    • Faraz

                      not sure about that
                      last time the error popped in this very section

                    • Fingers crossed then!

                    • Faraz

                      it Worked!!
                      Thanks you Mark you are genius
                      now all what remains is to get the bootcamp drivers lol

                    • YES!! I was rooting for you! Yup that should be a breeze. Just make sure whenever it needs to reboot like with updates or even bootcamp drivers that you do the option boot and chose efi. Also you won’t be able to chose bootcamp as startup disk in system preferences on Mac. Option at boot is how you will have to get to it.

                    • Faraz

                      that is not going to be a problem all i need to figure out now is how to get the drivers,
                      If you have got them send me a link

                    • That was in step 1 using boot camp assistant to download them. I’ll get the direct download link for you though. Which year is your MacBook Pro retina 13in?

                    • Faraz

                      retina 13 inch early 2015

                    • They don’t have one specific to 2015 but I used the latest one for 2013 and up modes. Mine is mid 2014. So these should work.

                    • Faraz

                      thanks a lot man!
                      downloading it right away
                      my internet is kind of slow so if you are up to something i’d suggest to resume it as its going to be a while
                      once again thanks a lot man!!

                    • Oh don’t worry I’ve been doing all this on my phone it’s no problem. Just at thanksgiving waiting for food to be done. You are very welcome. Let me know if those drivers work!

                      You’re downloading in windows right? Because that would be easiest.

                    • Faraz

                      happy thanksgiving man!

                  • faraz

                    i think it froze at 95%

                    • It might sit there for a while it’s not completely accurate. It may sit there for hours.


    i didnt use cmd until it was time for the deploy of .wim.But guys i have one serious oh wait…… 2 actually
    1. I formatted my segate 1 tb hdd and partitiond into 3 one bout 800 gb healthy,another 350 mb healthy primary and active fat 32 and bout 100 gb of ntfs logical partition and all i wanted to ask was if i had to now installother oses on it like any linux distros can i make other partitions more?

    2. The .wim fie i used is a AIO of win8 32 and 64 bits so how would the setup go after i choose the efi boot after running the bootloader in my MBA?


    • Faraz

      imagex.exe /info C:install.wim
      this command returns the xml file containing all the windows versions present
      choose the version that suits mostly win 8 pro 64 bit
      and regarding the linux destros I have no idea

  • jae won choi I’m having a bit of issue with this… I’m not sure on how to fix this

    • jae won choi

      Whoops wrong picture- It should’ve been the one with the error saying that It cant be installed on the drive connected to USB or port (dont remember) or EFI with MBR and should use GPT…..

      • If you could upload the photo of the error it would help greatly.

  • Alexandre

    Hi !
    I read the discussion between you and Faraz, I followed the tuto step by step, and I didn’t see the EFI boot, I see only Macintosh HD (my mac) and Windows. When I select windows, I have a BSOD when starting. I don’t know what to do. I hope that you can help me, I did the tuto like 5 times. (I use a windows 7 for the diskpart part).

    Thanks !

    • As I said in another comment, sorry for the delay in responding. Are you sure you did the steps correctly on the partitioning in diskpart and made the volume “active?” Step 17 for reference.

      • Benedikt M.

        Same problem here, did it multiple times, no EFI boot here…
        However on a win 8.1 pc the /f ALL didn’t work and on win 10 it just gives out examples for bcdboot. With the win 7 command it says it worked, but still no EFI…

  • Sarim Abbas

    Hi I have a Macbook Air mid-2012 running Sierra. Your guide worked great, but after a few moments playing around in Windows the screen went black/blank. Luckily I had managed to install a VNC client just before and am able to operate windows via RealVNC. I tried installing the bootcamp drivers as well as Intel Graphics 4000 drivers to no avail. Would appreciate some help thank you.

    • Sorry about the delay, could you give me some more information? What version of windows are you using? What machine did you use to setup the usb harddrive?

  • Charles Oliver

    I’ve followed this guide with my 2016 MacBook Pro with TouchBar and get pretty close to success. However…

    All seems to go well, apart from when I get to the initial install GUI for Windows 10 (first reboot after copying install files etc.)

    No input seems to be detected with the internal trackpad and keyboard or the magic trackpad 2 and magic keyboard I have paired over bluetooth.

    Has anyone else encountered these issues or managed to install on the latest MBP? I’d try a standard USB keyboard and mouse, but don’t have one to hand right now.

    • I haven’t tested this method on the 2015 MacBook Pros, but I assume that the Windows installer doesn’t have the drivers for the input that the new keyboard and trackpad uses. Bluetooth won’t work in this instance, so the Magic trackpad and keyboard won’t work. I would use a USB keyboard and mouse. All you really need is the mouse though.

      • Charles Oliver

        Nailed it. Used a cheapy USB keyboard with a USB C adapter and It’s all working beautifully. Tweaked some of the partitioning so I’ve got 200gb exfat for file transfer.

        Thanks ever so much for your article, Mark.

        • Glad it worked! Enjoy! I’m happy to hear that it works on the 2016 Macbook Pros.

  • Dimos Galatakis

    The process worked flawlessly for me. But I have an issue I don’t know if anyone else here has. I can’t activate my Windows with my licence key I keep getting hit with an error code 0xc004f050. The key is valid for what it’s worth

  • अनुराग पौडेल

    Guys i have a problem after doing all the steps above i landed to “windows cannot be configured on this hardware problem” previously when i did the above steps with win8 running in parallels and copying windows 8’s install.wim .It worked perfectly but now when i did that with win 10 in virtual machine and copying windows 10’s install.wim i get the error above plz help.

  • Mike

    Great guide, but the external drive is not showing up as a boot option when I restart the Mac and hold down the option key. I’m trying to do an install of Windows 8.1 on an external HDD and the iMac is a late-2011 model running Sierra. Aside from following all the steps again, is there any issue with getting everything to work with this setup?

  • TCB13

    I did successfully in the past with windows 10. But now I tried it again with Windows 10 Creator Update and after the first reboot I get a blue screen with the message INACCESSIBLE_BOOT_DEVICE. Any tips?

    • TCB13

      I also tried GPT and Master Boot Record, I’m able to get into the first boot “configuring devices” etc but after the second boot always get that error. My guess is that its something related to this version of windows…

      • I’m going to do some testing and report back. I’ve been wanting to try GPT and I haven’t tried it on the latest Creative Update. I’ll let you know.

        • TCB13

          I was able to use GPT on the previous version without issues. Even with a TimeMachine CoreStorage Apple Encrypted Volume on the same disk.

        • TCB13

          hey@Mark:disqus I tested Win10_1607 (pre creators update) and I still got the INACCESSIBLE_BOOT_DEVICE error. I also tested 3 different versions of imagex. First the version you provided, then the version from Microsoft target at windows Win10_1607 and then the latest version, of them caused the same error.

          So, seems like the issues it not the creators update but on of the two:
          1) some issue with a pre-creators update
          2) some issue related to my computer / specific case

          Waiting for your feedback.

          • Where are you getting your iso from?

            • TCB13

              @Mark From Microsoft itself: ms-website /software-download/windows10ISO (can’t post the real link because the post disappears…

              Ironically the ISO I used +6 months ago was from TPB but I don’t have it anymore to test. I do know that on that ISO I had to convert the ESD to WIM and on Microsoft’s official ISO it is already a WIM file.

        • TCB13

          @Mark_The_Tech:disqus just found the cause of this issue. It’s related to USB 3.0 and Windows boot. My external hard drive is USB 3.0 but seems like Windows can’t start from it when running in 3.0. If I connect a USB2 adapter between the computer and the hard drive it boots just fine without the INACCESSIBLE_BOOT_DEVICE error.

          Why? I watched carefully the boot process and concluded the following:

          – Windows seems to turn off and on all USB device during boot (I noticed this because my USB mouse just goes off for some seconds);
          – USB 3.0 devices like the hard drive seem not be brought back when windows turns USB on again. I’m not sure why this is happening but it is;
          – Running the same disk with the USB2 adapter will cause it to spin up again after windows turns USB devices on again;

          I did some research and found out that there are numerous knows issues with USB 3 devices and the boot process, especially on computers with Intel USB like my MacBook Air.

          If you have any suggestions on how to fix this issue I will be grateful!

        • TCB13

          @mark@Mark_The_Tech:disqus is it normal for windows to say that it’s running as a Windows to Go workspace? The previous version I used, before all this issues wasn’t saying that.

  • Andrei

    Hi, I followed all the steps carefully and when I’m booting from the mac I’m only seeing macOS, no EFI option. Any ideas ?

    • TCB13

      Is the HD spinning when you press alt? Did you hear it making noise? In my case sometimes I need to unplug it and plug again while on the boot menu and wait a few seconds.

      • Andrei Lovin

        I’m trying to install on a SSD, so no spinning is involved. I tried restarting the mac a couple of times but don’t remember if I unplugged and plugged the SSD while running. I’ll give it a try again. But could there be another issue involved in my mac not seeing the SSD.