How to Find and Delete Duplicate Files on Mac

An installer downloaded twice becomes "Installer (1).dmg". Photos get imported from your phone a second time. While tidying up, you copy a whole folder just in case. A single duplicate doesn't look like much, but together they can add up to several gigabytes, sometimes tens of gigabytes.

#Where duplicates come from

• Browsers download the same file again and add a number to its name.
• Photos and videos are imported more than once, or saved again from a messaging app.
• Whole folders get copied as a quick backup.
• Several sync services sync the same set of files.
• The same archive gets extracted more than once.

#Same name doesn't mean same content

Report.pdf and Report (1).pdf might be the same file, or two different versions. Meanwhile, a renamed video can be identical to the original down to the last byte. The reliable test is to compare file contents; names and modification dates are only hints.

One more thing that's easy to miss: when you copy a file in the Finder on the same APFS disk, the copy can share storage with the original until one of them changes. Delete one of those copies and you free less space than its size suggests.

#Find and check duplicates by hand

#First pass in the Finder

Open a folder where copies tend to pile up, such as Downloads, and switch to list view. Sort by Size and files of exactly the same size end up next to each other, which makes likely copies easy to spot. Sort by Name and files with a number or the word "copy" in their names line up beside the originals. If you're not sure, select a file and press the Space bar to compare the contents.

#Confirm in Terminal that two files match

In Terminal, type shasum -a 256 (with a space at the end), drag the two files into the window, then press Return. If the long string at the start of both output lines is identical, the two files have the same content.

To check a whole folder at once, run the command below. It lists files with identical content, and files in the same group share the same checksum:

find ~/Downloads -type f -size +10M -exec shasum -a 256 {} + 2>/dev/null | sort | awk '$1==prev {if (!shown) print last; print; shown=1; next} {prev=$1; last=$0; shown=0}'

This command only reads files and changes nothing. It has to read every file in full, so the more files in scope, the longer it takes. Adjust the path and the +10M size threshold as needed.

#Let the Photos app handle photos

Your Photos library is managed by the Photos app. Don't use Show Package Contents to open it and delete files inside, or you risk damaging the library. To deal with duplicate photos and videos in the library, open Photos, click Duplicates below Utilities in the sidebar, select the items you want to merge, then click Merge [number] Items. The extra items move to Recently Deleted, where you can recover them for 30 days.

#Decide which copy to keep

• Keep the copy that's in use: video projects, design files and code projects refer to their assets by path, so keep the copy they actually use.
• Intentional backups aren't clutter: copies on a backup drive or in a backup folder are there in case something goes wrong.
• Synced folders sync deletions too: delete a file in iCloud Drive or another synced folder, and the copies on your other devices are usually deleted as well.
• Leave identical files inside apps alone: identical files inside app bundles and ~/Library are normally managed by the apps, and deleting one can break an app.

#Find duplicates by content with WashBear

Duplicate Cleanup compares file contents and groups files that are exactly the same, even when their names differ. When two folders have identical contents, they appear as one group of identical folders.

1. Choose a scope: in the location selector at the top right, select Common Folders, recently used folders or disks, or click Choose folder… to add another location. You can select several at once.
2. Set a threshold: Minimum file defaults to 200 KB and can be changed to 1 MB, 10 MB, 100 MB or 500 MB. If space is your main goal, start with larger files.
3. Protect important locations: each selected location shows Cleanable on its right; click it to switch to Protected. Protected locations are still compared, but files in them are never deleted. For example, mark a backup folder as protected and Downloads as cleanable to find the files in Downloads that duplicate your backup. If your scope includes the Pictures folder that holds your Photos library, mark it as protected too.
4. Smart select: when the scan finishes, click Smart select to keep one file in each group and select the other copies. Use the arrow next to it to switch to Keep the file with the shortest path (the default), Keep the file with the shortest name, Keep the earliest modified file or Keep the most recently modified file. If a group contains protected files, all of them are kept.
5. Confirm and delete: expand each group to check paths and modification times, then click Delete Permanently. The bottom bar shows the Estimated space to free; the amount each group can reclaim up to is a ceiling, and the space actually freed may be less.

System folders, /Applications and /Library at the root of the disk, and files inside app bundles are skipped automatically, and ~/Library is scanned only when you choose it as the scope directly. See Duplicate File Cleanup for more.

#Frequently asked questions

#Can it find similar photos?

No. Duplicate Cleanup only finds files with exactly the same content. Burst shots and photos that were cropped, re-exported or compressed no longer match, so they won't be grouped together. Use the Photos app to choose between similar photos.

#There aren't many duplicates, but I'm still short on space. What next?

Then copies aren't the problem. Look for the largest files on your Mac, or read Mac System Data too large?