How to Find and Delete Duplicate Files on Mac

Duplicates build up in Downloads, in old project folders and in "final_v2_REAL" files. Removing them frees space, and the risk is deleting the one copy that mattered. This guide finds true duplicates and deletes them in a way you can undo.

How sure can you be that two files match?#

Names can mislead and sizes can coincide, so the contents settle the question.

Method 1: Finder, for a quick look#

1. Open the folder in Finder and press ⌘ J to open View Options. Tick Size columns if you use list view.
2. Switch to list view with ⌘ 2 and sort by Name to see "copy" and "(1)" files side by side.
3. Sort by Size to spot files with identical sizes next to each other.
4. Select a pair and press Space to Quick Look both before you decide.

Finder's File → Find with a Smart Folder can also list files by Kind and size, which helps in a large folder. This only suggests duplicates. Confirm with the next method.

Method 2: Terminal, for certainty#

This compares contents. It works on any folder, and it only reads files.

$ find ~/Downloads -type f -exec shasum -a 256 {} + | sort > ~/Desktop/hashes.txt

Then list only the files that share a checksum with another:

$ awk 'NR==FNR{n[$1]++;next} n[$1]>1' ~/Desktop/hashes.txt ~/Desktop/hashes.txt

Your output looks like this. These three files are identical:

87428fc5…25c7  ./1.txt
87428fc5…25c7  ./2.txt
87428fc5…25c7  ./sub dir/copy of 1.txt

Folder names with spaces or symbols trip people up in Terminal. Our Terminal path helper turns any path into a version that pastes safely.

Where not to look#

Some folders hold files that look like duplicates but are not.

• Photos, Music and Final Cut libraries. These are packages. Files inside are linked to a database. Deleting them by hand corrupts the library. Use the app instead.
• Application packages (.app). Parts of apps repeat on purpose.
• System and Library folders. Many files exist in several places by design.
• Cloud-synced folders, until sync finishes. Deleting there deletes everywhere.

For photos, open Photos → Albums → Utilities → Duplicates, which groups items that Photos considers duplicates and lets you merge them. For music, open the Music app and choose File → Library → Show Duplicate Items.

The safe deletion routine#

One surprise about space#

On APFS, a copy made inside the same volume can share storage with the original until you edit it. Deleting such a copy may free less space than the file's size suggests. That is normal and says nothing about your method.

When an app makes sense#

If you have thousands of duplicates across photos, music and documents, a dedicated finder gives you a guided review. We cover the options in Best Duplicate File Finders for Mac, including a free tool, dupeGuru, and a paid one, Gemini 2. For a wider clean-up, see Best Mac Cleaning Software.

Frequently asked questions#

How do I find duplicate photos?#

Use Photos → Albums → Utilities → Duplicates. It understands the library, which Finder does not.

Is it safe to delete a file with a matching checksum?#

Yes, as long as you keep one copy and the files are not part of a library, app or sync folder. Matching checksums mean the contents are the same.

Will deleting duplicates make my Mac faster?#

It frees space, which helps if your disk is nearly full. It will not speed up a Mac with plenty of room. See why a MacBook runs slowly.

Do I need a paid duplicate finder?#

Not for a few folders. A paid tool saves time on big, mixed libraries.