DMG File – What Is It & How to Open/Create It on Windows/Mac?

What Is DMG File

DMG file is an Apple Disk Image file. It is also called a Mac OS X Disk Image file, which is a digital reconstruction of a physical disk. DMG is typically a file format used to store compressed software installers without having to use a physical disc. You will most likely only see them when downloading macOS software from the internet.

This macOS disk image format supports compression, file spanning, and encryption, so some DMG files may be password protected. DMG files also support 128-bit and 256-bit AES encryption, which means you can create password-protected compressed folders.

Why Do You Need DMG File?

The main reason macOS uses DMG files is to ensure that the files are downloaded correctly and have not been tampered with. DMG files contain something called a checksum, which basically verifies that the file is 100% intact.

This small window first goes through a stage of validating the file and then proceeds to unzip it once it is sure that the file is good. That’s the second reason macOS uses DMG files – they’re a compressed format that keep your downloads smaller.

How to Open DMG File on Windows/Mac

How to Open DMG File on Mac

You can open DMG files by double-clicking the file. Once the file is clicked, the DiskImageMounter utility bundled with macOS verifies the integrity of the disk image. After confirming the disk image, the utility mounts the virtual disk and places it on your desktop and in Apple Finder windows as if it were a CD or USB flash drive inserted into your computer.

You can double-click the program icon in a Finder window to run the application. Alternatively, you can drag the program icon to the Applications folder icon in the same window, move it to the Applications directory on your computer, and then double-click the application directly from the Applications directory to run it.

How to Open the DMG File on Windows

A DMG file not only stores compressed files such as images and videos but also contains a software program. You can use one of the programs mentioned below to extract/open a DMG file in Windows, but you can’t execute the program and use it like you can with other Windows applications. To use the same program in Windows, you need to download the Windows version, not the Mac DMG version.

However, assuming the DMG files only contain files such as images or videos (which may also be in a Windows-compatible format), or that you just want to view the contents of the DMG file, you should have no problem viewing them with 7-Zip.

How to Create the DMG File

How to create the OMG file on Mac? Here are the steps:

Open Disk Utility and choose File > New Image > Image from Folder. In the window, select the folder you want to encrypt and click the Choose button.

Then, you can configure some additional options, like where to save the file and whether to use encryption. When you encrypt the folder, your Mac will prompt you to enter your password twice.

Also, by default, the DMG file is read-only. If you want a read-write DMG, change the Image Format option from Compressed to Read/Write.

When you go to open your new DMG file, it will prompt you for the password you chose. After typing the password, the DMG file will mount like any other.

Tips for Using DMG File

The following are two tips for using the DMG file.

1. Use the Correct File

If you’re on a Windows computer, look for a similar file named ISO. Using this type of file avoids the need for extraction tools. You also don’t need to download the application files in macOS format. Look for files with this file extension, if possible.

2. Use DMG Files Like a Flash Drive

A DMG file acts as if a separate device were transmitting information to your computer. Think of this download as a way to avoid plugging another storage system into your computer. Downloading a DMG file may take less time than traditional information transfer from a flash drive or CD to your device.