How to Convert a .DMG to a .ISO Using Terminal

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One of the most frequent questions I get is how to convert a Mac disk image file (dmg) to a more Windows friendly iso file. Fortunatly it’s not that hard, and there’s two ways to do it. In this article I’m going to show you how to accomplish this using only Terminal. For an explanation on converting the file using a graphical interface, see my other Bukisa article “How to Convert a .DMG to a .ISO Using Disk Utility.


Step 1. Open up Terminal from the Utilities folder in your Applications. Type in

hdiutil convert /path/to/file.dmg -format UDTO -o /path/to/newfile.iso

substituting /path/to/file.dmg with your DMG file and path/to/newfile.iso with where you want the new file to go (and what you want to name it).

Step 2. Hit enter and the prompt should run. Depending on your hardware and how big the file is, this might take a while. For this example my DMG was only 5.3MB so it took less than a second. On bigger DVD images this could take a much longer time.

Step 3. You’ll notice that what was created is an iso.cdr image. This is an ISO file with a fancy extension. We need to rename it to .iso, and then we’ll be done. You can do this manually of course, but while we’re in Terminal, let’s stick to that. Type in mv /path/to/file.iso.cdr /path/to/newfile.iso and hit enter. You now have a ISO file compatible with virtually any burning software.

Additional Tips

  • Feeling adventurous? Try writing an applescript that does this all for you.
  • Always check your new file before deleting the old one.

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