HOWTO: Convert an ISO file to DMG file

Mac OSX Leopard Disk Utility Icon


When using your Mac you have so much at your fingertips that it really makes you wonder how you ever used Windows.

Maybe you didn’t use Windows! But most of us have at one time or another.

This very short article give you two different ways to convert an ISO file to a DMG file using your Mac, OS X and no additional software to download. It’s built right into OS X.


Option 1 – Using Disk Utility

OS X’s Disk Utility is a powerful tool. Be cautious when using this as you could easily wipe out data on some of your disks if you’re not careful!

  1. Open Finder and then open Disk Utility by clicking Go > Utilities > Disk Utility
  2. When Disk Utility opens, click the Convert icon on the toolbar
  3. When prompted, browse to the ISO file you would like to convert, select it and click the Convert button
  4. Now you will be prompted for a name.  Ensure you give it a name with the extension .dmg
  5. Select Compressed from the Image format dropdown box and click Save
  6. Depending on the size of your file, you’ll soon have a DMG file version of your ISO file!

Option 2 – Using Terminal

From the lovely graphics of Disk Utility to the plain and simple command line of Terminal…

  1. Open Finder and then open Terminal by clicking Go > Terminal
  2. Type the following command but replace the filenames and paths with your own:
  3. hdiutil convert /path/filename.iso -format UDRW -o /path/filename.dmg

  4. Wait a few minutes (or few hours) depending on the size of your ISO and you will be returned to the terminal prompt when it’s finished.

HOWTO: Set The Default Program To Open Certain File Types in Mac OS X (EG: jpg, gif, etc)

Mac OS X Open With...Description

It can be quite annoying when you double click a file and it opens a program you don’t want or expect.

This HOWTO article describes the simple process of setting the default program on your Mac that opens any file type.
You’ll mostly want to open pictures such as jpg, gif, etc with a certain program but you can apply this solution to almost any file type.


  • When you double click a particular file or type of file in Finder or from your desktop the wrong program opens the file
  • You are presented with a dialog box saying There is no default application specified to open the document….


In OSX, most files have an extension which is usually 3 characters long. For example, some common picture files are usually .jpg, .gif, .tif and .png. Files with these extensions will behave in one of two ways when double clicked –

  1. Launch a program associated with the file extension OR
  2. OSX will prompt you with the message: There is no default application specified to open the document…

The solutions below will discuss both situations and how to select or change the desired program that launches your file.

Solution 1 – Change Registered File Type

  1. In Finder or from your Desktop, right click or CTRL+Click on the file that you want to change the launch program for
  2. Click Get Info. The info box will appear
  3. The fourth section down from General is the Open With... section. Click the down arrow on the field in this section and either choose an application or select Other to browse for an application elsewhere on your Mac.
  4. When you have selected an application you can either close the Info box and this will just make the selected file open with your chosen application or you can click the Change All… button.
  5. If you click the Change All.. button you will then be asked for confirmation that you want all similar documents to open with your chosen application. Click Continue if this is what you want.
  6. Close the Info box and you’re done!

Solution 2 – Use ‘Open With…’ Context Menu Option

  1. In Finder or from your Desktop, right click or CTRL+Click on the file that you want to change the launch program for
  2. Select Open With and then select Other…
  3. When the Choose Application dialog appears locate the application you want to use for opening the selected file type and then place a check mark in the box Always Open With
  4. Click Open
  5. Your file will open in your chosen application and the selected file will always open with that application from now on
Mac OS X Finder: Open With.... Context Menu

Mac OS X Finder: Open With.... Context Menu

A helpful tip. This method will only change the default launch program for the selected file and not all files of the same type. For all files, use Solution 1 above.