How to Find Old Disk Images Hidden on Your Mac

Disk images are macOS’s all-purpose container format. App developers use DMGs to distribute software. Time Machine uses sparsebundles for network backups. FileVault and encrypted disk utilities create sparseimages. People making bootable USB drives have ISOs hanging around.

Each is a self-contained virtual volume that can be mounted as if it were a drive. And each one is potentially eating large chunks of your storage. A single old sparsebundle from a discontinued network backup can hit 200GB. ISOs of operating systems you tested are often 4-12GB each.

Here’s how to find every disk image on your Mac, identify which are still useful, and clear the rest.

The disk image formats macOS uses

Before searching, knowing what to look for helps:

• .dmg — Standard disk image. Most app downloads.
• .iso — Disk format used for CD/DVD images and OS installers.
• .sparseimage — Older expandable encrypted image. Grows as you add data.
• .sparsebundle — Modern bundle-format image. Used by Time Machine and similar. Stored as a folder with banded data files inside.
• .cdr — DVD master format. Rare but Apple uses it for some media.
• .toast — Roxio Toast format. Mostly historical.
• .img — Raw disk image, used in some development scenarios.

Smart Folder for disk images

Open Finder. Choose File → New Smart Folder. Click “This Mac.”

Hit + to add a criterion. Set Kind to “Disk Image.” This catches DMG, sparseimage, and most other Apple-recognized formats.

For ISOs specifically, sometimes Spotlight categorizes them differently. Add a second criterion for File Extension = iso.

For sparsebundles — these are folders, not files. Smart Folder needs different handling. Set Kind = Folder, then add Filename ends with .sparsebundle.

Save the search and sort by Size. Disk images tend to skew large, so the top of this list is where the storage went.

Finding sparsebundles specifically

Sparsebundles are common backup containers and can be huge. Find them with:

find / -type d -name "*.sparsebundle" 2>/dev/null

The -type d flag is critical — sparsebundles are directories, not files. With sizes:

find / -type d -name "*.sparsebundle" -exec du -sh {} + 2>/dev/null | sort -hr

Common locations:

• ~/Library/Mobile Documents (rare but possible)
• /Volumes/[network drive] (Time Machine over network)
• ~/Library/Application Support/[backup app]
• External drives with old backups

Time Machine creates sparsebundles for network backups. If you stopped using a particular network drive, an old sparsebundle may still exist on the originating Mac’s connected volumes.

Spotlight from the command line

mdfind queries by content type:

mdfind 'kMDItemContentType == "com.apple.disk-image-udif"'

That’s read-only DMG. For all DMG variants:

mdfind 'kMDItemKind == "Disk Image"'

For ISOs:

mdfind 'kMDItemKind == "Disc Image"'

(Note: “Disc” with a c, Apple’s distinction.)

For everything in a single search using extension:

mdfind 'kMDItemFSName == "*.dmg" || kMDItemFSName == "*.iso" || kMDItemFSName == "*.sparseimage"'

To filter by size:

mdfind 'kMDItemKind == "Disk Image" && kMDItemFSSize > 1073741824'

Disk images over 1GB.

The find approach for thoroughness

find doesn’t depend on Spotlight indexing:

find ~ -type f \( -name "*.dmg" -o -name "*.iso" -o -name "*.sparseimage" -o -name "*.cdr" -o -name "*.img" \) 2>/dev/null

Plus directories for sparsebundles:

find ~ -type d -name "*.sparsebundle" 2>/dev/null

To run both in one go and see sizes:

{ find ~ -type f \( -name "*.dmg" -o -name "*.iso" -o -name "*.sparseimage" \) ; find ~ -type d -name "*.sparsebundle" ; } 2>/dev/null | xargs -I {} du -sh "{}" 2>/dev/null | sort -hr

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Where each type tends to hide

DMGs in ~/Downloads, ~/Desktop, ~/Documents.

ISOs in ~/Downloads, ~/Documents, sometimes ~/Movies (people store them there because they’re large media-like files).

Sparseimages in ~/Documents, /Volumes if encrypted volumes were left mounted from external drives, or ~/Library/Application Support for apps that use encrypted containers.

Sparsebundles in /Volumes/[network share], ~/Library/Application Support, or on external drives. Old Time Machine backups are the heaviest culprits.

.img files mostly in ~/Downloads when downloading Linux distributions, Raspberry Pi OS images, or similar.

Mounting before deleting

If you’re not sure what’s inside a disk image, mount it first.

Double-click the file. macOS mounts it and shows the contents in Finder. Browse to see what it actually contains. If it’s an old app installer for software you have, the install version probably matches or is older than what’s already on your Mac.

For sparseimages, double-click also mounts them. You’ll be prompted for a password if they’re encrypted.

After verification, eject the mounted volume (Cmd+E or right-click in sidebar → Eject), then delete the source file.

For ISOs of operating systems, the mounted contents are typically a bunch of OS installer files. If the OS in question isn’t something you’re actively testing, the ISO can go.

What’s safe to delete

Always safe:

• DMGs older than 90 days for apps you have installed
• ISOs of operating systems you’ve already installed elsewhere or aren’t using
• Old Time Machine sparsebundles when you’ve moved to a different backup destination
• Test/demo disk images you used once

Probably safe:

• Encrypted sparseimages you can’t remember the password to (verify nothing important inside first)
• Old game installers from services that still let you redownload (Steam, GOG, App Store)
• Driver installers for hardware you still use

Keep these:

• Sparseimages used as your active encrypted vault
• Sparsebundles for active backups (don’t delete a Time Machine backup you’re still using)
• Custom-made disk images for specific projects

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Compacting a sparseimage instead of deleting

If you have a sparseimage you want to keep but it’s grown larger than its current contents need, you can compact it. Sparseimages don’t shrink automatically when you delete files inside.

hdiutil compact /path/to/your.sparseimage

That reclaims unused space inside. Doesn’t change capacity — just removes the slack.

For sparsebundles, similar:

hdiutil compact /path/to/your.sparsebundle

Disk Utility’s First Aid

Sometimes a corrupted disk image takes more space than its actual contents because of internal errors. Disk Utility can verify and repair:

1. Open Disk Utility (Applications → Utilities → Disk Utility)
2. Choose File → Open Disk Image and select the file
3. Click the mounted image in the sidebar
4. Click “First Aid” and run it

This won’t always free space but can fix issues that prevent compacting.

A note on Time Machine sparsebundles

If you have multiple Macs and have used Time Machine over a network at some point, sparsebundles for old Macs may exist on your current backup destination. They’re easy to spot — the filename usually includes the source Mac’s name.

To list all sparsebundles on a connected backup volume:

ls -lh /Volumes/[backup drive name]/*.sparsebundle

Old ones from Macs you no longer use can be deleted. Active ones (the one your current Mac backs up to) should not be deleted while Time Machine is using them — pause Time Machine first.

A regular sweep

Disk images don’t accumulate as constantly as some other categories, but they’re individually large. A quarterly check is enough.

Open the Smart Folder. Sort by Size. For each entry: do I still need this? When did I last mount it? Is the source available if I needed it again?

For Macs where the disk image collection is large and disorganized, a cleaning tool can flag old DMGs, ISOs, and sparseimages alongside other deletion candidates. The catalog work happens automatically.

Either way, disk images are some of the biggest single deletions you can make on a Mac. Each one is a self-contained file with a known size, often redundant once whatever it contained has been used.