Can You Delete DMG Files on Mac After Installing an App?
Yes, you can usually delete a downloaded .dmg after the app inside has actually been copied to Applications and opens from there. A .dmg is a disk-image file: double-clicking it mounts a volume, but mounting is not installation. If you launch the app straight from that volume, deleting or ejecting the image may stop that copy from working.
A .pkg is different: it runs an installer that can place files beyond Applications. After the installer completes and the installed software works, its downloaded package is usually disposable too. Keep either file if you need an offline reinstall or that particular older version is difficult to obtain again.
Check where the app is running from
- Open the downloaded
.dmg. Its mounted volume appears in Finder, often in the sidebar under Locations. - If it contains an app and an Applications shortcut, drag the app to Applications and wait for the copy to finish. If it contains an installer instead, run the installer and finish its steps. Apple's installation guide covers both disk images and packages.
- Eject the mounted volume in Finder, then open the app from Applications. If it opens with the image ejected, the installed copy no longer depends on that mounted image.
- Only then move the downloaded
.dmgto the Trash. Empty the Trash when you are certain you no longer need that installer; until then it remains recoverable there.
If Finder says the disk cannot be ejected because it is in use, quit the app or close documents opened from that volume and try again. Apple gives the same guidance. Do not treat a mounted image's app icon, a Dock shortcut, or an open window as proof that a separate copy was installed.
Which file is safe to remove?
| File you found | What to verify before deleting it |
|---|---|
Downloaded app .dmg |
The app was copied out of the mounted image and opens from Applications after ejection |
Downloaded installer .pkg |
The installer finished and the software it installed opens or works as expected |
| App still opening from a mounted image | Copy or install it first; the mounted image is still its current location |
| Old installer kept for offline use | Confirm that you no longer need that exact version or can get it again |
| A disk image you created for documents or an encrypted archive | Inspect and back up its contents; the image itself may be your only copy of the data |
The last row is the important exception. Disk Utility can create a disk image for files and folders, including encrypted images. Its .dmg extension does not make it an expendable installer. Open it and identify what it contains before deleting it; if it holds unique documents, keep an independent backup.
Moving a downloaded installer to the Trash also does not uninstall software that was already installed. To remove the app and its related data, use its own uninstaller when one is provided, especially for software with helpers or extensions. A package can leave files and receipts outside the app; uninstalling a .pkg app is a separate job.
When keeping an installer makes sense
Keep the installer if the Mac must be set up without internet, your organization needs a specific tested version, or the developer may no longer offer that release. Store it somewhere intentional rather than leaving a pile of unidentified downloads. Deleting it saves disk space but may mean downloading it again later, if that version remains available.
For ordinary downloads, the useful test is simple: eject the image, launch the installed copy, then remove the download. If the goal is to find other large files, use macOS Storage to see disk usage, not a blanket rule that every .dmg should go.
FAQ
Can I delete a .dmg while the app is open?
First establish whether the app is running from the mounted image or from Applications. Quit it, eject the image, and reopen the installed copy. If the image cannot be ejected because it is in use, do not assume installation is complete.
Does deleting a .dmg uninstall the app?
No. The downloaded image and an app copied to Applications are separate files. Removing the image only removes that installer copy.
Can I delete a .pkg after installation?
Usually, yes, after the installer has finished and the installed software works. Keep the package if you need an offline or exact-version reinstall; deleting it does not undo the installation.
Are all .dmg files installers?
No. A disk image can contain personal files or be an encrypted archive. Check its contents before treating it as a downloaded app installer.