Written by
Amanda Wong
Even if the latest Mac operating system is macOS 14 Sonoma, some Mac users may want to install macOS Big Sur on their Macs. If you want to downgrade to macOS Big Sur from Monterey/Ventura/Sonoma, install macOS Big Sur on a virtual machine, or create a bootable Big Sur USB Mac, you must get the macOS Big Sur DMG file.
A macOS Big Sur DMG file is a disk image file containing the installer for macOS Big Sur. With it, you can install macOS Big Sur on Mac, run macOS Big Sur on a virtual machine on Mac, and create a bootable disk. DMG is a Mac-only format. Thus, if you want to run macOS Big Sur on a virtual machine that isn't a Mac, you need to download the macOS Big Sur ISO file.
Get the macOS Big Sur DMG file directly
If you want to get the macOS Big Sur DMG file directly on your Mac for virtual machine or bootable USB, you can click the links below:
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Create a macOS Big Sur DMG file step-by-step
In case the macOS Big Sur DMG file of the minor version you want is not available, you can create the macOS Big Sur DMG file manually. First of all, you need to get the macOS Big Sur installer.
On Mac running macOS Ventura and later, you can't find macOS Mojave/Catalina/Big Sur in App Store, just click the link below to download macOS Big Sur 11.7.10 from the Mac App Store.
The installer of macOS Big Sur is around 12 GB, make sure there is enough Mac disk space for it and ensure a good network connection for the downloading process. If you need to free up disk space on Mac, try iBoysoft DiskGeeker to easily remove junk files on Mac.
Download macOS Big Sur in App Store
Click the Get button and it will guide you to the System Update in System Settings and display the download process bar.
The macOS Big Sur installer downloaded from the Mac App Store is a pkg file, and you need to take further steps to create a macOS Big Sur DMG file with it. You should first open the downloaded InstallAssistant.pkg file to install the macOS Big Sur installer in the Applications folder, then you can proceed to create a macOS Big Sur DMG file with the Disk Utility or via the Terminal.
Create macOS Big Sur DMG file with Disk Utility
Disk Utility, the macOS built-in tool allows you to create disk images on Mac, you can follow the steps below to create a macOS Big Sur DMG file using Disk Utility:
- Access the installer named "Install macOS Big Sur.app" in Applications from Finder.
- Right-click it and choose copy then paste it into a new folder on your desktop.
- Go to the Disk Utility, click File from the top app menu, and select New Image > Image from Folder.
- Select the new folder where you paste the Big Sur installer, and click Choose > Save.
- When it is created, eject the macOS Big Sur file.
Create macOS Big Sur DMG file via Terminal
- Launch Terminal from the Applications > Utilities.
- Enter the command below and press Enter to create the disk image DMG file destination and temporary volume.hdiutil create -o /tmp/MacOSBigSur -size 16500m -volname MacOSBigSur -layout SPUD -fs HFS+J
- Mount the Big Sur.dmg file. hdiutil attach /tmp/MacOSBigSur.dmg -noverify -mountpoint /Volumes/MacOSBigSur
- Use createinstallmedia utility to copy the installer files to the created disk image DMG file: sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MacOSBigSur --nointeraction
- Type in your admin password and hit Enter.
- Type Y to confirm the erase process.
- Wait for the process to finish.
- Unmount the macOS Big Sur disk. [hdiutil detach /Volumes/MacOSBigSur/
- Move the macOS Big Sur DMG file to your desktop for easy access:mv /tmp/MacOSBigSur.dmg ~/Desktop/
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