How to Create a Disk Image on a Mac

What is a disk image on Mac?

A disk image is an exact replica of a disk or partition. It can be used for backup purposes or to save space by storing only a copy of large, infrequently used files. Disk images come in various formats, making them compatible with different types of computers, including Windows, macOS, and Linux. In macOS, the disk image format is .dmg.

How do I create a disk image on a Mac?

On a Mac, there is a program called Disk Utility. It's what Mac users can use to erase, format, and mount disks. As a disk management tool for the Mac, you can also use it to create disk images for your Mac.

Create a Disk Image on a Mac

Step 1: Open Disk Utility and choose File > New Image > Blank Image.

Step 2: Type in a name for the disk image, add a tag if you want, and choose a location to save it. This is what will show up in Finder, where you'll need to save the disk image file before opening it.

Step 3: In the “Name” field, enter a name for the disk image. This is what will display in the Desktop and Finder sidebar when the disk image is open.

< strong >Step 4. Enter a size for the disk image in the Size field.

Step 5: Click the Format pop-up menu, and choose a format for the disk:

• If the disk will be used with a Mac, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled). • If the disk will be used with both Windows and Mac computers and is 32 GB or smaller, choose MS-DOS (FAT). • If the disk will be used with both Windows and Mac computers and is larger than 32 GB, choose ExFAT. • To encrypt the disk image, click the Encrypt pop-up menu, then choose an encryption option.

# Partition and format the disk image

Step 1: Click the Partition pop-up menu, and choose a partition layout.

Step 2: Click the Image Format pop-up menu, then choose an option:

• Sparse bundle: Similar to a sparse image, but the directory data in the image is stored differently. Uses the .sparsebundle extension. • Sparse disk image: Creates an expandable file that grows and shrinks as needed. Doesn't use extra space. Uses the .sparseimage extension. • Read/write: Allows you to add files to the image after you create it. Uses the .dmg extension. • DVD/CD master: Resizes the image to 177 MB (for an 8-cm CD). Uses the .cdr extension.

Step 3: Click Save, and then click Finish.

To use a disk image, double-click it to mount it. If the image is encrypted, enter the password when prompted. After mounting the image, you can access its contents in Finder as you would any other disk. When you're finished, drag the image to the Trash, or eject it from the menu bar by choosing Disk Utility > Eject.

The Benefits of Creating an Disk Image

Whether you're creating a disk image for a Mac or Windows, the functionality and benefits of a disk image are the same. Disk images have many advantages. For example, you can use a disk image to:

• Install software on multiple computers without downloading it each time. • Copy files to disks or volumes that can't be copied with the Finder. • Create bootable disks or partitions. • Restore a disk or volume to its original state.

Bonus Tip: How to Backup Your Mac Without Time Machine

Aside from Disk Utility, there is another built-in tool on Mac called Time Machine. Different from Disk Utility, Time Machine only has one function – backing up Mac data. Here, we recommend a third-party Mac backup software – Todo Backup for Mac. It allows you to back up your Mac to an external hard drive or other storage device in 3 simple steps.

You can directly search “AOMEI Todo Backup for Mac” on Google, or download and install this software for free. It allows you to back up Mac data without Time Machine under all Mac OS X systems:

Step 1. Launch and run Todo Backup for Mac. Click on the first Backup tab, or directly hit the + button at the bottom left to create a backup task – name your backup task and then click OK.

Step 2. Choose the backup destination, where you want to store your Mac files as a backup, the frequency of automatic backups, and then click OK.

Step 3. Add files and folders to your backup set.
Click Add Files+ to choose which ones you want to include in your backup, then hit the blue Start button to back up your Mac to another drive or external device.

How to Clone Hard Drive on Mac

Download the most popular Mac cloning software to clone Mac hard drive to SSD without re-installing the OS and apps.

Bottom line

Now that you know how to create a disk image on Mac and the benefits of having one, feel free to make your own by following the steps above. If you have any other concerns, please don't hesitate to drop a comment below. Thanks for reading!