How to Find Duplicate Photos on Mac the Fast Way

If your Photos library is past 50GB, there’s a real chance 5-15GB of it is duplicates. The pattern’s predictable: you imported from your iPhone, then imported again later from a backup, then synced from iCloud, then exported and re-imported. By the time you notice, you’ve got three copies of half your library.

Apple finally added a real solution to Photos in macOS Ventura 13. It works well. Most people don’t know it exists. Here’s how to use it, plus what to do about photos sitting outside the Photos library.

The native Duplicates album

In Photos for Mac (Ventura 13 and later, including Sonoma 14 and Sequoia 15), open the app and look at the sidebar. You should see “Duplicates” under the Library section.

Click it. Photos shows you groups of duplicates, with a “Merge X items” button on each group. Each group includes:

• The actual photo
• The number of copies
• Total size of the duplicates
• A merge button

Photos identifies duplicates using image hashing — meaning it catches the same photo even if it was saved at different sizes, in different formats (JPEG vs. HEIC vs. PNG), or with different metadata. This is more sophisticated than simple file-comparison.

When you click Merge, Photos keeps the highest-resolution version and deletes the rest. Metadata gets combined — captions, keywords, album memberships, edits all preserved on the kept copy.

Why the Duplicates album is sometimes empty

The Duplicates album doesn’t appear immediately on first launch. Photos has to scan your entire library, and depending on size, this takes anywhere from 20 minutes to several hours.

Things that block or slow the scan:

• iCloud Photo Library still syncing (let it finish)
• Photos app not in the foreground for long enough (leave it open in front)
• Mac asleep (disable App Nap on Photos, or just keep the Mac awake)
• Library size — a 200GB library takes longer than a 20GB one

If you’ve waited a day and Duplicates is still empty, force a re-analysis. There’s no UI button for this, but quitting Photos and restarting often kicks it back into action. Or rebuild the library: hold Cmd+Option while launching Photos → choose Repair Library. Slow but thorough.

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Working through a giant Duplicates album

If you’ve got hundreds or thousands of duplicates, merging one group at a time is exhausting. Faster approach:

1. In the Duplicates album, hit Cmd+A to select everything visible
2. Then either: click “Merge X items” with everything selected (handles all groups at once)
3. Confirm the merge dialog

You’ll see a “This will merge X duplicate groups” message. After confirming, Photos works through them all. Can take 5-30 minutes depending on count. Don’t quit Photos during this.

After the merge, the duplicates go to Recently Deleted. They stick around for 30 days as a safety net. To free the space immediately:

1. Sidebar → Recently Deleted
2. Cmd+A → Delete All

Or wait the 30 days and let them auto-purge. Either works. If you’re tight on storage right now, manually emptying is faster.

What about photos outside the Photos library?

Plenty of photos live outside the Photos library — in Desktop, Documents, AirDrop folders, Downloads, or random subfolders. Photos’ Duplicates album doesn’t see those.

For non-library photos, you have a few options:

The “Add to Photos” route: drag the loose photos into Photos. They get imported, and the Duplicates album catches matches between them and existing library photos. The downside is your Photos library grows temporarily before you clean up.

Manual hunt by file size: sort suspicious folders by size. Two JPEGs with the exact same byte count are almost always duplicates. Doesn’t catch format-converted duplicates, but works for the easy cases.

A standalone tool: specialized duplicate-finders compare image content directly. They can catch a JPEG and a HEIC of the same photo. Most charge for the privilege.

For most people, the right move is consolidating everything into Photos first, then using the native Duplicates album to clean up.

The Photos library size after cleanup

Cleaning duplicates often doesn’t immediately shrink the visible library size. Two reasons:

1. Photos keeps thumbnails in resources/derivatives even for deleted originals. These rebuild over time.
2. iCloud Photo Library may take hours or days to fully reflect the deletions across your other devices.

To check the actual size: quit Photos, then in Finder, navigate to ~/Pictures/Photos Library.photoslibrary (or wherever your library lives). Right-click → Get Info. The size shown is your actual library size on disk.

After cleanup, that number should drop substantially. If it doesn’t drop within a day, the cache derivatives are probably the holdup. They thin themselves over a week or two as Photos clears them in the background.

Beyond duplicates: other ways to shrink Photos

Once you’ve handled duplicates, a few more storage-saving moves:

1. Switch to “Optimize Mac Storage.” Photos → Settings → iCloud. With this on, Photos keeps thumbnails locally and pulls full resolution on demand. For most users, this saves 50-90% of library size on the Mac.
2. Delete old screenshots from your library. Photos’ built-in Screenshots album makes this easy. Most are throwaway after a few days.
3. Delete bursts. Burst photos (taken on iPhone) often have 10+ shots; you usually want one. Use the Bursts album in Photos.
4. Review Slo-Mo and Cinematic videos. They take serious space (often 500MB+ per minute). Use the Slo-Mo and Cinematic albums to find them.

For Optimize Mac Storage specifically: it’s the highest-impact change you can make to your Photos library size. The downside is offline access — if you’re on a plane and try to open a photo that’s been thinned, you see only the thumbnail until you’re back online.

When Photos identifies wrong “duplicates”

Photos’ duplicate detection isn’t perfect. Common false positives:

• Two photos taken seconds apart of the same scene (similar but not identical)
• A photo and its edited version (Photos sometimes treats them as duplicates)
• Identical thumbnails for different full photos (rare)

Always glance at the duplicate group before merging. If you see two clearly different photos grouped, click each thumbnail to compare full-size, then choose individually. The “Merge X items” button on each group can be skipped — you can use the Trash icon on individual photos within a group instead.

When in doubt, skip the merge. Re-running the duplicate scan later will catch it again if it really is a duplicate.

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What about iPhone photos still on the phone?

If your duplicates exist on iPhone too, deleting them on Mac with iCloud Photo Library enabled removes them from iPhone too. That’s the whole point of iCloud — one library, multiple devices.

If you have iCloud Photo Library off and want to clean both, you’ll need to do it on each device separately. Photos for iOS doesn’t have a Duplicates album (as of iOS 17), but the same hashes-based dedupe works through iCloud sync.

For iPhone photos that have never made it to Mac: either turn on iCloud Photo Library and let it sync, or manually import via Image Capture (Cmd+Space → “Image Capture” → plug in iPhone → import).

Maintenance after the first big cleanup

Once you’ve done the first thorough pass, ongoing maintenance is light:

• Run Duplicates album quarterly (takes 5 minutes)
• After importing from a backup or new device, run it immediately
• Periodically empty Recently Deleted to actually reclaim space

A typical first-pass cleanup on a 100GB library frees 5-20GB. Subsequent passes typically free 1-3GB at a time, which is just the duplicates that crept in since the last pass.

The honest take: Apple solved the photo duplicate problem properly when they added the Duplicates album. Before that, you needed third-party tools, and most of them were either expensive or unreliable. Now, the native option is genuinely good for the Photos library specifically. For loose photos outside Photos, you’re back to manual or third-party tools — but those are usually a smaller chunk of your overall problem.