dmg file extension.ĭVD/CD master: Changes the size of the image to 177 MB (CD 8 cm). Read/write disk image: Allows you to add files to the disk image after it’s created. Sparse disk image: Creates an expandable file that shrinks and grows as needed. Sparse bundle disk image: Same as a sparse disk image (below), but the directory data for the image is stored differently. To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.Ĭlick the Partitions pop-up menu, then choose a partition layout.Ĭlick the Image Format pop-up menu, then choose an option: If the disk image will be used with a Mac or Windows computer and is 32 GB or less, choose MS-DOS (FAT) if it’s over 32 GB, choose ExFAT. If the disk image will be used with a Mac with macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled). If the disk image will be used with a Mac that has a solid state drive (SSD) and uses macOS 10.13 or later, choose APFS or APFS (Case-sensitive). In the Size field, enter a size for the disk image.Ĭlick the Format pop-up menu, then choose the format for the disk:

This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.

In the Name field, enter the name for the disk image. This is the name that appears in the Finder, where you save the disk image file before opening it. In the Disk Utility app on your Mac, choose File > New Image > Blank Image.Įnter a filename for the disk image, add tags if necessary, then choose where to save it. You can create an empty disk image, add data to it, then use it to create disks, CDs, or DVDs.

Backup mac disk image