File type: Mac OS X Disk Image

Open DMG File

The usage of the DMG file extension is in the context of a mountable disk image file which is generated by the Mac OS X Operating System platform. Once the file is opened, the system will mount it in a virtual disk located on the user's desktop.

This type of file is normally utilized for the distribution of software installation packages for the Macintosh computer system.

Prior to the introduction of this file format, the Mac environment utilized the IMG up until the introduction of the Mac OS 9. The Apple Disk Utility is the main application associated by users to this particular file type under the Macintosh platform and is bundled with the Mac OS X installation package.

Unmount the dmg file named “Install macOS Sierra.dmg” (if it is mounted:) Go to the top menu of “Disk Utility” window and select “images” and then “Scan image for restore” Go to the “Install macOS Sierra.dmg” and click open. Now you are able to restore the dmg-file to your usb drive. How to get Catalina - if you are running Catalina. Open the Mac App Store. Go to the Catalina page, you can click this link to Catalina on the Mac App Store. Now, if you click on Get, your Mac will offer to download the installers.

Although not meant to be directly opened under the Microsoft Windows Operating System platform, the DMG format file can be accessed by Windows users by using some third party applications in the market. Basically, the DMG file extension can be compared to the EXE or ISO format of Windows and can even function as a complete virtual drive for the system.

The mimicking of physical CD drives is a workaround implemented by the system to address problems that may arise from CD requirements of some software programs including support for the efficient usage of an organization's resources.

Detailed information

File format: Proprietary

Open with Windows: Acute Systems TransMac, DMG2IMG or DMG2ISO

The DMG format file is also used by video games distributed for the Macintosh computer environment which are commonly protection enabled.

This format makes sure that all software installation and execution in the system are carried out correctly by providing support for both physical and virtual drives required by the system.

Running an application from a virtual drive may also allow a user to execute a program without actually copying an instance of it in the physical storage drive of the computer system.

This will save storage space and proves to be advantageous especially for programs which are not used very often. Aside from the Apple tool bundled with the Operating System, other more commonly used utilities that serve as an alternative include MagicISO, IsoBuster, and UltraISO.

These programs are more popularly executed under the Windows environment but are capable of reading DMG file formats and compressing them into another file extension that is more popularly used.

Another example of this conversion program is the DMG2ISO.

These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.

Download macOS

Find the appropriate download link in the upgrade instructions for each macOS version:

Boot Mac From Dmg File Download

macOS Catalina, macOS Mojave, and macOS High Sierra download directly to your Applications folder as an app named Install macOS Catalina, Install macOS Mojave or Install macOS High Sierra. If the installer opens after downloading, quit it without continuing installation.
To get the required installer, download from a Mac that is using macOS Sierra 10.12.5 or later or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.
macOS Sierra downloads as a disk image that contains a file named InstallOS.pkg. Open this file and follow the onscreen instructions. It installs an app named Install macOS Sierra into your Applications folder.
OS X El Capitan downloads as a disk image that contains a file named InstallMacOSX.pkg. Open this file and follow the onscreen instructions. It installs an app named Install OS X El Capitan into your Applications folder.

Use the 'createinstallmedia' command in Terminal

Connect the USB flash drive or other volume that you're using for the bootable installer. Make sure that it has at least 12GB of available storage and is formatted as Mac OS Extended.
Open Terminal, which is in the Utilities folder of your Applications folder.
Type or paste one of the following commands in Terminal. These assume that the installer is still in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in these commands with the name of your volume.
Catalina:*
Mojave:*

High Sierra:*
Sierra:
El Capitan:
Press Return after typing the command.
When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the bootable installer is created.
When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Catalina. You can now quit Terminal and eject the volume.

Install Dmg On Mac

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument, similar to the way this argument is used in the commands for Sierra and El Capitan.

Use the bootable installer

After creating the bootable installer, follow these steps to use it:

Boot Mac From Dmg Files

Plug the bootable installer into a compatible Mac.
Use Startup Manager or Startup Disk preferences to select the bootable installer as the startup disk, then start up from it. Your Mac will start up to macOS Recovery.
Learn about selecting a startup disk, including what to do if your Mac doesn't start up from it.
Choose your language, if prompted.
A bootable installer doesn't download macOS from the Internet, but it does require the Internet to get information specific to your Mac model, such as firmware updates. If you need to connect to a Wi-Fi network, use the Wi-Fi menu in the menu bar.
Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

For more information about the createinstallmedia command and the arguments that you can use with it, make sure that the macOS installer is in your Applications folder, then enter this path in Terminal:

Catalina:

Mojave:

High Sierra:

Sierra:

El Capitan: