Sparse image (Mac)
Also known as: sparseimage, sparse bundle, Mac sparse disk image, .sparseimage
A sparse image is a macOS disk-image type that only uses as much real storage as the data it actually contains, growing as you add files. It is used for encrypted containers and for backups like Time Machine over a network.
- macOS image that grows as data is added
- Used for encrypted containers and network Time Machine
- Created in Disk Utility; mounts as a volume
A disk image that grows on demand
A normal disk image reserves its full size up front. A sparse image (.sparseimage) or sparse bundle allocates space only as files are added, so a large-capacity image can take little real disk until it fills up.
This makes sparse images handy as encrypted, expandable containers on macOS — a mounted volume that protects its contents and only consumes the space it needs.
Where sparse images appear
Disk Utility can create encrypted sparse images for storing sensitive files. Time Machine uses sparse bundles when backing up to a network share, packaging the backup as a single growing image.
Double-click to mount one as a volume; it appears in Finder until ejected.