Find duplicate files on your Mac and remove the extra copies

Where duplicate files come from

Nobody makes duplicates on purpose. The same attachment is saved twice, a file is downloaded again because it was quicker than finding it, a folder is copied "just in case" before a change, photos are imported from a card and also exported from an app, a backup folder is copied in from an old Mac. Browsers and Finder name the second copy report (1).pdf or report copy.pdf, but just as often the copies have different names in different folders.

Searching by name misses those, and matches files that only share a name. The reliable way to find duplicate files is to compare their contents.

Matched by contents, byte for byte

Tidy My Mac compares what is inside the files, in three steps, so it never reads more than it has to:

1. Files are grouped by size. A file with no other file of exactly the same size can't have a duplicate, and is never read.
2. Files that share a size have their first and last 64 KB hashed. Most files that differ are told apart here.
3. Only files that still match are read in full and compared with a SHA-256 hash of their whole contents.

Files that match all the way through are listed together as one group, largest space to free first, with how many copies there are and how big each one is. A counter shows how much has been compared, and you can cancel at any time.

Which copy to keep

Each group puts the copy it suggests keeping first, marked Keep, with the reason it was chosen:

• a copy in Documents, Pictures, Movies, Music or the Desktop, where people file things on purpose, over one anywhere else, and anywhere else over Downloads;
• then a copy whose name doesn't look like a copy, over photo (1).jpg or report copy.pdf;
• then the oldest copy, which is usually the original;
• then the one with the shortest path.

Select All but Kept ticks every other copy at once, or you can tick copies one by one. Quick Look and Show in Finder are next to every copy.

Space you would really get back

On APFS, the file system every modern Mac uses, a copy made in Finder is often a clone: it shares its data with the original and takes almost no extra space. A file still held by a Time Machine snapshot doesn't free its space either. Tidy My Mac asks the file system how much deleting each copy would actually free, and shows that, not the copies' total size. When the two differ, the group explains why.

A file with several hard links is counted once, since deleting one link frees nothing.

What is left out, and why

Some copies are meant to be there. Your Library folder, hidden folders, code repositories, node_modules, app bundles, frameworks, Photos libraries and virtual machines are skipped, because an app or a project expects each of those files at its own path and removing one would break it. Files smaller than the minimum you choose, 1 MB, 10 MB or 100 MB, are skipped too, and so are iCloud files that are not downloaded to this Mac, since reading them would download them.

For near-identical photos rather than exact copies, use Photos, which compares what pictures look like.

Your home folder, or any folder

By default Duplicates looks through your home folder, as part of the same scan that fills the Disk Map, Large Files and the Junk Cleaner. Choose Choose Folder… to look through one folder instead, such as an external drive or a folder of old backups.

Removing duplicates safely

Copies you remove are moved to the Trash, never deleted outright, and recorded in the cleanup history on the Dashboard, where Put Back returns them. The comparison runs on your Mac, and no file or hash leaves it; the Privacy Policy has the details. Until you grant Full Disk Access, a home-folder scan leaves out Desktop, Documents and Downloads rather than raising a macOS prompt for each.