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, 2010 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, 2011 at 5:04
  • I need 10 more reputation points to answer or I would. ;)
    – spyderdyne
    Jun 2, 2021 at 23:14

3 Answers 3


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.)

  • 11
    It's worth noting that replacing /dev/diskN with /dev/rdiskN in the dd command will usually make the process immensely faster on Mac. Jan 11, 2015 at 18:00
  • @RyanPendleton 3900907520 bytes transferred in 39.042057 secs (99915522 bytes/sec) I would say that's a noteworthy addition. May 5, 2016 at 20:42
  • 2
    I had to use bs=1M, my dd didn't like lower-case m. Jun 22, 2016 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, 2016 at 7:49
  • 1
    Didn't boot for me either. I tried with a Win7 64bit Ultimate iso. This sucks
    – GeneCode
    Dec 4, 2020 at 13:12

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...


This is a very old topic but needs some update.

First, Windows 7 is no longer supported by modern Mac. So unless you want to use the installation disk on a PC or old Mac, then Windows 10 is more recommended.

Second, please try to format the USB to FAT32 instead of NTFS or exFAT, which will does not work on Mac. (NTFS is not supported by Mac natively and exFAT won't be recognized as a bootable device in Boot Menu.)

dd command should get the job done for most of cases. However, if you are not a fan of command line, then you can switch to UUByte ISO Editor app (how-to tutorial) or build a Windows virtual machine, which has more free and reliable tools for creating bootable USB from ISO.

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