Apple delivers the macOS installer and applications through the app store since the launch of OS X Lion. The macOS installer has a .app extension when you get it through the official channel. Unlike the macOS DMG installer, which Apple doesn’t provide nowadays, the app version of the macOS install package is not bootable. Hence it is not mountable nor compatible with operating systems like Windows. For some reason, if you want macOS in .DMG or .ISO format, there is a method to convert the .app file. Unfortunately you need a macOS system to convert .app to .dmg to .iso image.
Reasons for converting macOS Mojave or High Sierra .app to .DMG or .ISO
- The macOS in DMG format let to quickly create Install DVDs and USB installers in a few minutes.
- When you convert macOS Install .app to ISO format, you may use it for running macOS on Windows PCs (Hackintosh).
- DMG converted from the macOS Install app is usable from a Windows computer for creating bootable macOS installer. By this way, you could fix a faulty iMac or MacBook Air/Pro with a PC.
Above all, DMG and ISO files are highly portable; it is easy for anyone to upload and transfer them through the Internet.
Convert macOS Installer .APP to .DMG bootable image
The requirement for running macOS, and a USB Pen Drive for converting the Installer application to bootable ISO or DMG image. The step by step process for converting macOS Mojave, High Sierra, Sierra, EI Capitan to the bootable .DMG or .ISO is explained below.
- First of all, download the latest version of macOS from the App Store and confirm that it is in the Applications folder.
- Next step is to create a bootable USB installer from macOS Install app. The macOS installer is then saved to bootable DMG format.
- I prefer using the macOS Terminal app to create the bootable USB Installer, using the instructions on the Apple website.
- Open macOS Terminal app, and type one of the commands based on your macOS version.
- Remember to change the text “MyVolume” with the name of your USB device.
- Finally, press the Enter key and put your admin password to create macOS installer medium on your USB.
- Now, open the Disk Utility application.
- From the External devices list, find your newly created macOS Installation disk (USB).
- Right- click on USB icon, and choose the option ” image from Install macOS” and save it.
- The system now starts converting the macOS installer (.app) on your USB to bootable .DMG file.
The output is a boot-friendly DMG image which you could restore to a USB drive from any macOS system.
Double click on the macOS Install DMG file to check whether it is bootable. If yes, you will see a notification, “macOS detected.” It is also possible to burn this DMG file to a DVD or USB Pen Drive from Windows PCs using software like Transmac.
Just in case you find difficulty, check our video on in converting your copy of macOS .app to bootable .dmg.
How to convert macOS .dmg to .iso format.
There is no direct way to convert macOS .app to .ISO bootable image. You need to carry out APP to DMG conversion on a mac before you could make it an ISO, CDR or IMG file. The Disk Utility app in macOS previously had an option that allows you to convert DMG to ISO/CDR. There is also a Terminal command to convert .DMG files to .ISO in macOS environment. Unfortunately, I couldn’t get those methods working on macOS High Sierra for converting the Mojave to a USB bootable installer. Hence, I’m suggesting an effective alternative here.
I’m using a macOS software called AnyToISO to convert macOS app to iso format. The free version of AnyToISO doesn’t support converting dmg files above 850 MB. Hence, you need to either purchase or download (Search AnyToISO Pro 3.9.0 in Google) the PRO version of this app.
In my experience, converting DMG to ISO takes a lot of space and resources if you’re on macOS machine. The system shows out of space notification even though you have enough space left in the disk. Therefore, it is better to transfer the DMG files to a Windows machine and use freeware like DMGtoISO to for converting. Check our page on burning DMG on windows for freeware tools supporting DMG to ISO conversion.