How to find and delete duplicate photos on a Mac

Duplicate photos on a Mac sit in two different places, and each place needs a different fix. The Photos app can clear the copies inside its own library. The copies in your folders and on your external hard drives are invisible to it, and that’s usually the bigger pile.

So there are two ways to remove duplicate photos on a Mac, and the one you need depends on where your photos live. If all of them are in the Photos app, the next section finishes the job for free. If you also have photos in folders, exports you saved somewhere, or an external hard drive with three copies of the same wedding on it, read past it.

Where the duplicate photos came from

They almost never arrive on purpose. Four common ways the same photo lands on your Mac twice:

• You imported the same memory card twice, a month apart.
• You copied a folder to an external hard drive for safekeeping, then copied it again the next year.
• You kept a working copy: Photos 2019, Photos 2019 copy, Photos 2019 FINAL.
• You saved the same image twice out of one message thread.

Each of those is a separate moment, which is why the copies end up in separate places. Nothing looks wrong until your storage fills up. Then you go looking for duplicate photos on a Mac that has been collecting them for four years, and they’re spread across the Photos app, a few folders, and a drive you haven’t plugged in since 2023.

How to delete duplicate photos in the Photos app

The Photos app reads the library you have open and gathers the duplicate photos and videos it finds in one place.

1. Open the Photos app.
2. Click Duplicates under Utilities in the sidebar. If nothing appears under Utilities, hold your pointer over it and click the reveal control. If Duplicates still isn’t there, the Photos app either found no copies or hasn’t finished reading your library, and a big library takes a while.
3. If you use iCloud Shared Photo Library, click the Library pop-up in the toolbar and choose Both Libraries.
4. Select the sets you want to clear. Command-A selects all of them.
5. Click Merge, then confirm.

One original stays where each set used to be, and the copies move to Recently Deleted, where you have 30 days to change your mind. If you have iCloud Photos turned on, the merge syncs out to your iPhone and iPad, so do this on the Mac and leave your phone alone.

That’s the whole built-in feature. On a Mac where every photo lives in the Photos app, it removes the duplicate photos you have and costs nothing.

What the Duplicates collection never sees

The Duplicates collection reads one Photos library, the one you have open. Duplicate photos anywhere else on your Mac are invisible to it:

• Photos in regular folders: your desktop, your downloads folder, Documents.
• Anything on an external hard drive, plugged in or not.
• A second Photos library on a drive, unless you open that one instead.
• Exports. As soon as you export a photo to a folder, that copy sits outside the library.
• Anything that isn’t a photo or a video, including the duplicate PDFs and installers sharing the drive.

So the Duplicates collection can come back empty while 40 GB of the same shoot sits in three folders on an external hard drive. It answers a smaller question than the one you asked.

Duplicates are one piece of a full disk. If your Mac keeps warning you about storage, how to free up disk space on a Mac covers the rest of it, from the Storage screen to the Downloads folder.

How to find duplicate photos in folders and on drives

Let’s take the three options in the order most people try them.

Look through Finder yourself

Open the folder in list view, click the Size column, and look for pairs sitting next to each other at the same size. That catches the obvious ones.

Then it runs out. Finder compares names, dates and sizes, never the contents of a file. IMG_4412.jpg and wedding-ceremony-14.jpg can be the same photo, and Finder has no way to tell you. Two different photos can share a size and look like a match. Across two hard drives, forget it.

Get an exact list from Terminal

If you’re comfortable in Terminal, macOS can build the list for you. This reads your files and prints what it finds. It deletes nothing.

cd ~/Pictures/camera-imports
find . -type f -exec shasum {} + | sort | awk '{ hash=$1; sub(/^[^ ]+ +/, ""); group[hash]=group[hash] "\n  " $0; n[hash]++ } END { for (h in n) if (n[h] > 1) print "duplicate set:" group[h] }'

Point the first line at the folder you want to check, then run the second one. Every set of files with identical contents prints together, whatever they’re named:

duplicate set:
  ./2021/IMG_4412.jpg
  ./sorted/wedding-ceremony-14.jpg
  ./backup/IMG_4412.jpg

Run it on your external hard drive too, by pointing cd at /Volumes/YourDriveName. Two things to know before you rely on it. It matches on file contents, so a resized export of the same shot counts as a different file and won’t appear. And the deleting is still yours to do by hand, with no thumbnails to check against.

Use an app that compares file contents

Past a few thousand photos, or more than one hard drive, an app earns its place. Any duplicate file finder for Mac you point at your photos should do four things:

• Move copies to the macOS Trash, so a mistake is recoverable.
• Refuse to remove the file you picked as the keeper.
• Show you the groups before anything moves.
• Tell you which copy it plans to keep, and let you change it.

If free and open source matters most, dupeGuru is a long-standing option. dupeGuru for Mac covers what it does well and what to check before installing it.

Using SupaDupa for the photos the Photos app never sees

SupaDupa is a Mac app built for that second half: the duplicate photos and files in your folders and on your hard drives, outside any photo library.

Point it at a folder or a hard drive you have plugged in. It reads everything, groups the files whose contents match, and puts the biggest recovery at the top. Photos, videos, PDFs, installers. For exact copies the file type doesn’t matter, which is why the total climbs faster than it does in a photo-only tool.

What to expect:

• Finding and trashing exact duplicates is free. No file limit and no scan limit.
• The oldest copy is the keeper by default. SupaDupa won’t trash that one, and every group keeps at least one file no matter what you select.
• Copies go to the macOS Trash, and the confirmation names the count before anything moves.
• There’s no undo button in the app once you trash a file. The copies are in your Trash, which is where you restore them from. Renames and moves do have undo in the app. Trashing doesn’t.
• It works on one connected folder at a time, so a shelf of hard drives takes a few passes.
• Look-alike photos are a Pro feature. Same shot, three exports, two resizes, which no exact-copy check will ever catch. It reads JPEG and PNG. HEIC and RAW files aren’t compared for look-alikes, though exact copies of them are still found.

One piece of advice that costs a sale and saves you an afternoon: don’t point SupaDupa at your Photos library. The Photos app manages what’s inside Photos Library.photoslibrary, and a file tool looking in there sees thousands of files it has no business moving. Let the Photos app handle its own library with the Duplicates collection above, and point SupaDupa at your folders, your downloads and your external hard drives.

Pro is $49, once. Everything in this guide is in the free version.

Before you trash anything

• Back up first. Time Machine, or a second copy of the drive. That’s true of any cleanup, with any tool.
• Keep the drive plugged in. A drive that disconnects partway leaves the job half done.
• Open one or two keepers and check them. Delete duplicate photos in one folder, look at what’s left, then run the rest.
• Your Trash still holds the files. Check your storage after you empty it, not before.
• Remember iCloud. If iCloud Photos is on, what you merge on the Mac syncs to your other devices.

Start in the Photos app, since it’s free and it takes minutes. Then remove duplicate photos from your folders and your external hard drives, where the rest of them have been sitting.