DMG File Extension

What is DMG file?

Files with the DMG extension are bootable disc images, supported in Mac OS X systems. This files are often encountered with installers of software downloaded from the internet. Such files are opened with the Apple Disk Utility application, which is used for mounting images in Apple devices. After being mounted, the image of a file is displayed in the standard file manager – Finder, as a new volume.

Additional information

DMG images may comprise of different types of file systems. Theoretically, it is possible to create also hybrid images, containing multiple file systems. Using Apple Disk Utility we can use an image as source for CDs or DVDs being recorded.

In some situations, DMG files may contain installation software necessary for installation of the programs contained within them, thus they do not require using any additional tools.

DMG files in different operating systems

In Mac OS X systems, the DMG files have substituted files stored in the IMG format in the previous version of the system: Mac OS Classic. Although DMG files are by default designed for devices running on Mac OS, there are tools which enable to converse them into formats supported by Windows. However, not every DMG image can be properly converted into format supported by Windows – furthermore, there is no guarantee, the image will be possible to operate on properly.

Programs which support DMG file extension

Below you will find an index of software programs that can be used to open DMG files divided into 3 categories according to system platform supported. Files with DMG extension, just like any other file formats, can be found on any operating system. The files in question may be transferred to other devices, be it mobile or stationary, yet not all systems may be capable of properly handling such files.

Updated: 12/07/2021

How to open file with DMG extension?

There can be multiple causes why you have problems with opening DMG files on given system. What is important, all common issues related to files with DMG extension can be resolved by the users themselves. The process is quick and doesn’t involve an IT expert. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Download and install 7-Zip

The main and most frequent cause precluding users form opening DMG files is that no program that can handle DMG files is installed on user’s system. This one is an easy one. Select 7-Zip or one of the recommended programs (for example, PeaZip, HFSExplorer, TransMac) and download it from appropriate source and install on your system. On the top of the page a list that contains all programs grouped based on operating systems supported can be found. One of the most risk-free method of downloading software is using links provided by official distributors. Visit 7-Zip website and download the installer.

Step 2. Check the version of 7-Zip and update if needed

If you already have 7-Zip installed on your systems and DMG files are still not opened properly, check if you have the latest version of the software. Sometimes software developers introduce new formats in place of that already supports along with newer versions of their applications. If you have an older version of 7-Zip installed, it may not support DMG format. The latest version of 7-Zip should support all file formats that where compatible with older versions of the software.

Step 3. Set the default application to open DMG files to 7-Zip

If you have the latest version of 7-Zip installed and the problem persists, select it as the default program to be used to manage DMG on your device. The method is quite simple and varies little across operating systems.

Change the default application in Windows

• Choose the Open with entry from the file menu accessed by right-mouse clicking on the DMG file
• Select Choose another app → More apps
• To finalize the process, select Look for another app on this PC entry and using the file explorer select the 7-Zip installation folder. Confirm by checking Always use this app to open DMG files box and clicking OK button.

Change the default application in Mac OS

• By clicking right mouse button on the selected DMG file open the file menu and choose Information
• Find the Open with option – click the title if its hidden
• Select the appropriate software and save your settings by clicking Change all
• If you followed the previous steps a message should appear: This change will be applied to all files with DMG extension. Next, click the Continue button to finalize the process.

Step 4. Check the DMG for errors

Should the problem still occur after following steps 1-3, check if the DMG file is valid. It is probable that the file is corrupted and thus cannot be accessed.

1. The DMG may be infected with malware – make sure to scan it with an antivirus tool.

Should it happed that the DMG is infected with a virus, this may be that cause that prevents you from accessing it. It is advised to scan the system for viruses and malware as soon as possible or use an online antivirus scanner. DMG file is infected with malware? Follow the steps suggested by your antivirus software.

2. Verify that the DMG file’s structure is intact

Did you receive the DMG file in question from a different person? Ask him/her to send it one more time. It is possible that the file has not been properly copied to a data storage and is incomplete and therefore cannot be opened. It could happen the the download process of file with DMG extension was interrupted and the file data is defective. Download the file again from the same source.

3. Verify whether your account has administrative rights

Sometimes in order to access files user need to have administrative privileges. Log in using an administrative account and see If this solves the problem.

4. Verify that your device fulfills the requirements to be able to open 7-Zip

If the system is under havy load, it may not be able to handle the program that you use to open files with DMG extension. In this case close the other applications.

5. Verify that your operating system and drivers are up to date

Up-to-date system and drivers not only makes your computer more secure, but also may solve problems with Mac OS X Disk Image file. It may be the case that the DMG files work properly with updated software that addresses some system bugs.

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