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What Is a DMG File and How to Open It on Mac?

Updated on Thursday, May 16, 2024

iBoysoft author Vain Rowe

Written by

Vain Rowe
Professional tech editor

Approved by

Jessica Shee


DMG file overview: what it is and how to open it

Summary: From this article by iBoysoft, you can learn about the DMG file, including what it is and what it is used for. In addition, it also tells you how to open a DMG file on Mac and Windows.

RAW file system

When you open the Download folder in Finder, you see a file with the .dmg file extension. What does it mean? That is called an Apple Disk Image file or DMG file in short. If you want to get more details about the DMG file, please move on.

What is a DMG file & what it is used for?

DMG is a file format mainly used to store and distribute compressed software installers for Mac devices.

Most of the time, you only see the DMG files when you download a program or software from the Internet. After downloading, it mounts as a disk on your Mac. You can copy the app from the DMG file to your Mac to finish installing. 

Therefore, a DMG file is always regarded as a virtual disk drive. Every time you open a DMG file, it will be auto-mounted and appear in Finder under the Locations tab, just like other physical disks. In addition, it will also show up in Disk Utility.

How to open a DMG file on Mac?

The Mac OS makes it easy to open a DMG file. As the DMG files are usually downloaded from browsers, you can find them in the Downloads folder in your Finder by default.

You just need to double-click your DMG file in Finder or other locations like the desktop. Then, the DMG file will be auto-mounted and opened up immediately.

The DMG file shows up in Finder

If the disk image couldn't be opened on your Mac via double-clicking and see an error message like "No mountable file system", the file may be already corrupted. You can download it once again.

How to run a DMG file on Windows?

The Mac DMG file is not compatible with Windows by default. To open and read a DMG file on Windows, you need to use a third-party tool. And you can compress the DMG to ZIP when transferring it.

In fact, you rarely need to open a DMG file on Windows because it is used to store the Mac-compatible software installer. If you want to install the same software on your Windows, you need to download its Windows version.

But if you want to open a self-created DMG file on a Windows computer, you can use 7-Zip. This free software allows you to open and read DMG files on Windows. 

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