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What is a DMG File?


Question: What is a DMG File?

Did you find a DMG file on your computer and wonder what program should open it? Maybe someone emailed you a DMG file but you're not sure how to use it. Perhaps you tried to open the DMG file but Windows told you that it could not open it.

Before you can open a DMG file (assuming it's even a file format that's intended to be viewed or edited), you'll need to determine what kind of file the .DMG file extension refers to.

Answer: A file with the DMG file extension is a Mac OS X Disk Image file.

Other types of files may also use the DMG file extension. If you know of any additional file formats that use the .DMG extension, please let me know so I can update this information.

How To Open a DMG File:

The easiest way to open a DMG file is to double-click on it and let your PC decide which default application should open the file. If no program opens the DMG file then you probably don't have an application installed that can view and/or edit DMG files.

Warning: Take great care when opening executable file formats received via email or downloaded from websites you're not familiar with. See my List of Executable File Extensions for a listing of file extensions to avoid and why.

On a Mac, DMG files are "mounted" as drives, making them really easy to view the contents of. Software you download for your Mac in a DMG format can be opened and then the setup program can be run to install the software.

If you're using Windows, you can open a DMG file with any compression/decompression program that supports the format. PeaZip and 7-Zip, both free, support DMG files. See this List of Free File Extractors for more choices.

If you know anything else useful about DMG files, please let me know so I can update this page.

Tip: Use Notepad or another text editor to open the DMG file. Many files are text-only files meaning no matter the file extension, a text editor may be able to properly display the file's contents. This may or may not be the case with DMG files but it's worth a try.

If you find that an application on your PC does try to open the DMG file but it's the wrong application or if you would rather have another installed program open DMG files, see my How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

How To Convert a DMG File

There are two main ways to attempt to convert a DMG file to another file type:

The first option involving opening the DMG file in its native program is preferable because it's both easier and will probably result in a more accurate file conversion. Of course if you don't have a program that opens DMG files, a third-party file conversion tool (the second option) could be very useful.

Important: You cannot usually change a file extension (like the DMG file extension) to one that your computer recognizes and expect the newly renamed file to be usable. An actual file format conversion using one of the methods described above must take place in most cases.

Still Having Problems Opening or Using a DMG File?

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more. Let me know what kinds of problems you're having with opening or using the DMG file and I'll see what I can do to help.

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