I was wondering if you know of a way of creating a Windows 7 USB installation disk on Mac OS.

  • I am using the dd command to copy the .iso image of the installation disk to the usb drive. It's taking so long! Over 40 minutes now. – AlexBrand Apr 21 '10 at 0:13
  • Yeah the sudo dd command works, seems your usb drive is slow. But for me it took around 35-40 minutes. so no point in suprising – MoG Apr 19 '11 at 5:04

Here are the steps to be performed on a Mac to create a Windows 7 USB Bootable Installation Drive.


  1. Open a Terminal (under Utilities)

  2. Run diskutil list and determine the device node assigned to your flash media (e.g., /dev/disk2)

  3. Run diskutil unmountDisk /dev/diskN (replace N with the disk number from the last command; in the previous example, N would be 2)

  4. Execute sudo dd if=/path/to/downloaded.iso of=/dev/rdiskN bs=1m (replace /path/to/downloaded.iso with the path to where the image file is located; for example, ./windows7.iso)

  5. Run diskutil eject /dev/diskN and remove your flash media when the command completes (this can take a few hours on slower drives)

(Note: The sudo dd command executes for around 5 minutes, depends on the USB port and drive.)

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    It's worth noting that replacing /dev/diskN with /dev/rdiskN in the dd command will usually make the process immensely faster on Mac. – Ryan Pendleton Jan 11 '15 at 18:00
  • @RyanPendleton 3900907520 bytes transferred in 39.042057 secs (99915522 bytes/sec) I would say that's a noteworthy addition. – Stephan Bijzitter May 5 '16 at 20:42
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    I had to use bs=1M, my dd didn't like lower-case m. – Matt Joiner Jun 22 '16 at 3:17
  • dd the iso file doesnt make the usb bootable, isn't it supposed to dd a img file instead? – Lamnk Aug 28 '16 at 7:49
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    Unfortunately doesn't boot, but thanks anyways. – Andrei Dec 8 '16 at 12:43

If you have access to a different Windows box, try the tool from Microsoft here. There are also manual instructions here. I don't know of any way of making a windows-bootable drive natively in Mac OS X.

I've recently been through this. No matter what I did, I couldn't get my MacBook Pro (can't remember exactly how old it is, but it identifies as "MacBook Pro 3,1") to boot a Windows install disk off anything except the internal SuperDrive, which unfortunately is broken. I tried more things than I can remember, including external DVD drive, USB key, USB hard drive, Firewire hard drive, EFI bootloaders, etc etc etc.

In the end I managed a hack using a trial version of Parallels Desktop - instructions here. If you have a different model Mac to mine, you might find rEFIt helpful - it's an EFI loader that you can run either from your hard drive or a USB key that should hopefully make the experience of booting into the windows install a bit easier...

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