How to install an app from a .dmg on Mac in one click

What a .dmg is, and why installing from one takes four steps

A .dmg is a disk image: a single file that macOS opens as if it were a disk. Double-click it and a new disk appears in the Finder sidebar, usually with a window showing the app and, beside it, a shortcut to your Applications folder with an arrow between them. That window is the developer’s way of saying “drag this there”.

Nothing is installed at that point. The app is sitting on a disk that only exists while the image is open. Installing means copying it into Applications; after that, the disk image has done its job, but it stays open in the sidebar until you eject it, and the .dmg file stays in Downloads until you delete it. So one install is four things to do: open, drag, eject, delete. Skip the last two a few times and you have a sidebar full of disks and a Downloads folder full of installers for apps you already have.

How to install an app from a .dmg by hand

Open the .dmg. Double-click it in Downloads. macOS may show a progress bar while it checks the image before the disk appears.

Drag the app into Applications. Drag it onto the Applications shortcut in the disk image’s window, or onto Applications in the Finder sidebar. Wait for the copy to finish.

Eject the disk image. Click the eject button next to its name in the Finder sidebar, or select it and press ⌘E, or Control-click it and choose Eject.

Delete the .dmg. Drag it from Downloads to the Trash. You can always download it again if you need it. It goes on using disk space until you empty the Trash.

Open the app from Applications. Open it from the Applications folder or with Spotlight, not from the disk image — that’s the copy that stays.

Some disk images hold an installer package (a .pkg) instead of an app. There’s nothing to drag: double-click the package and Apple’s Installer walks you through it, often asking for your Mac’s password. When it’s done, eject the disk image and delete the .dmg the same way.

The first time the app opens

macOS checks apps downloaded from the internet the first time you open them, and usually asks whether you’re sure you want to open an app you downloaded. That check happens however the app got into Applications.

If macOS says it can’t check the app or won’t open it, and you trust where it came from, go to System Settings → Privacy & Security soon after you tried to open it: there’s an Open Anyway button for that app. If you don’t know where the app came from, the safer answer is not to open it.

Common .dmg problems

The app opens, but from the disk image. If you double-click the app in the disk image’s window instead of dragging it, it runs from a disk that disappears when you eject it. Some apps notice and offer to move themselves to Applications; if yours doesn’t, quit it, drag it to Applications and open that copy.

The disk won’t eject. Usually the app is still running from it, or a Finder window or a file on it is still open. Quit the app and close the windows, then eject again. The same goes for any disk, and this guide to ejecting disks covers the rest, including ejecting several at once.

You can’t delete or rename the app inside the disk image. Disk images for apps are usually read-only, so nothing on the disk can be changed. Copy the app out first; then eject the disk.

The .dmg won’t open at all. A download that stopped part-way is the usual cause. Download it again from the developer’s site.

You now have two copies of the app. Dragging a new version onto an old one in Applications asks whether to replace it; choosing Keep Both leaves two. Delete the one you don’t want, and make sure the one in the Dock is the one you kept.

What the one-click install does, and what it leaves alone

With the fix on, opening a disk image that holds an app shows a card asking whether to install it in Applications. Nothing happens until you click Install. Then the app is copied, the disk image is ejected and the .dmg is moved to the Trash. Moving the .dmg to the Trash is on by default and can be turned off, and you can have the app open once it’s installed.

The app is copied as it is, so macOS still checks it the first time it opens, exactly as above. If you already have the app, it is never replaced without asking, and the old copy goes to the Trash rather than being deleted. If that copy is running, it’s replaced only after you agree to quit it.

For a disk image that holds an installer package, MacFixes only offers to open the installer, which then runs in its own window as usual. And if you just want a clean Mac after installing, quit the apps you’re not using on their own, too.

Permissions, and turning it off

More fixes macOS doesn’t give you

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