How to Move Your Photos Library to an External Drive on Mac (2026 Guide)

If your Mac's internal storage is groaning under the weight of years of photos and videos, knowing how to move your Photos Library to an external drive on Mac is one of the highest-impact things you can do to free up space. A typical library can run anywhere from a few gigabytes to several hundred gigabytes, and shifting it to a fast external SSD or a large spinning drive leaves your system volume lean and fast. This guide covers every step for macOS Sequoia and the forthcoming macOS Tahoe on both Apple Silicon and Intel Macs, so you can move your library safely and keep Photos working as if nothing changed.

How Large Is Your Photos Library, and Where Is It?

By default, macOS stores your Photos library at:

~/Pictures/Photos Library.photoslibrary

That path expands to something like /Users/yourname/Pictures/Photos Library.photoslibrary. Despite the .photoslibrary extension, it is actually a macOS package (a directory disguised as a file). Right-click it in Finder and choose Get Info to see its true size before you move it.

To get the size from Terminal:

du -sh ~/Pictures/"Photos Library.photoslibrary"

Libraries commonly reach 50–200 GB for regular users and well over 500 GB for photographers. If you're trying to understand what else is eating your disk, this overview of what takes up space on a Mac is a useful companion read.

What You Need Before You Start

• A formatted external drive. Format it as Mac OS Extended (Journaled) or APFS using Disk Utility. Avoid exFAT — Photos requires macOS-native extended attributes that exFAT cannot store reliably.
• Enough free space on the drive. You need at least as much free space as the library's current size, ideally 20% more.
• iCloud sync paused (optional but recommended). In Photos → Settings → iCloud, tick Pause so the library isn't modified mid-copy.
• Photos fully closed. Quit Photos before copying to avoid database corruption.
• A recent backup. Time Machine or a manual copy to a second drive. Moving a multi-hundred-gigabyte library is a perfect moment to confirm your backup is current.

How to Move Your Photos Library: Step-by-Step

These steps work on macOS Ventura, Sonoma, Sequoia, and the upcoming macOS Tahoe release.

1. Quit Photos completely. Press Command-Q or choose Photos → Quit Photos. Confirm it is not running in Activity Monitor.
2. Connect and verify your external drive. It should appear in the Finder sidebar. Confirm it is formatted APFS or Mac OS Extended by selecting it in Finder and pressing Command-I.
3. Copy the library — do not drag yet. Hold Option while dragging ~/Pictures/Photos Library.photoslibrary to your external drive. Holding Option forces a copy rather than a move, leaving the original intact as a safety net. Alternatively, use Finder's Edit → Copy and Edit → Paste Item on the external drive.
4. Wait for the copy to complete. For large libraries this can take from minutes to several hours depending on the connection type. Do not eject the drive or let the Mac sleep.
5. Verify the copy with Terminal. Compare checksums or at minimum compare sizes:

   du -sh ~/Pictures/"Photos Library.photoslibrary"
   du -sh /Volumes/YourDriveName/"Photos Library.photoslibrary"

   Both lines should report the same size.
6. Open the copied library in Photos. Hold Option and launch Photos. A dialog appears asking which library to open. Select the one on your external drive and click Choose Library.
7. Set it as the System Photo Library. Go to Photos → Settings → General and click Use as System Photo Library. This is required for iCloud Photos and Shared Albums to work correctly.
8. Confirm everything works. Browse your photos, check a few albums, and confirm iCloud sync resumes. Let it run for a few minutes.
9. Delete the original. Once you are confident the external copy is complete and healthy, move ~/Pictures/Photos Library.photoslibrary to the Trash and empty it. Do not skip this step — leaving both copies causes confusion and wastes space.

Using Terminal for the Copy (Power-User Method)

If you prefer the command line, rsync is more reliable than a Finder copy for large transfers because it can resume if interrupted:

rsync -avh --progress \
  ~/Pictures/"Photos Library.photoslibrary" \
  /Volumes/YourDriveName/

The flags mean: archive mode (preserves permissions, symlinks, timestamps), verbose, human-readable sizes, with progress. If the transfer stops mid-way, re-run the same command — rsync will skip files that already match and continue from where it left off.

Keeping Photos Happy Every Time the Drive Is Connected

Once the library lives on an external drive, Photos will show a "library not found" alert if you open it without the drive connected. A few habits help:

• Name the drive consistently. macOS mounts external drives under /Volumes/DriveName. If you rename the drive after setting up Photos, the app will lose track of the library path.
• Use a desktop alias (optional). In Finder, right-click Photos Library.photoslibrary on the external drive and choose Make Alias. Drag the alias to your Desktop or Dock for quick access.
• Disable Download Originals on the internal drive. If iCloud Photos is on, go to Photos → Settings → iCloud and switch from Download Originals to this Mac to Optimise Mac Storage while the library is on the external drive. This prevents iCloud from re-filling your internal SSD.
• Eject the drive safely. Always eject via Finder before unplugging. A hot-unplug during a sync write can corrupt the SQLite databases inside the package.

What Lives Inside the .photoslibrary Package

You rarely need to venture inside the package, but understanding its layout helps when troubleshooting. Right-click the library in Finder and choose Show Package Contents:

• originals/ — your original master files, organized into subfolders by a hex hash
• resources/ — thumbnails, derivatives, and face-recognition data
• database/ — SQLite databases that power the Photos UI (do not edit these by hand)
• private/com.apple.Photos/ — caches and temporary files Photos rebuilds automatically

The originals/ folder is the irreplaceable part. Everything else can be rebuilt by Photos if needed (though rebuilding face data can take hours on a large library).

Rebuilding the Library Database

If Photos behaves oddly after the move — thumbnails missing, albums empty — try a library repair. Hold Command-Option while launching Photos and choose Repair Library. Photos will rebuild its internal database from the originals. This is safe and non-destructive.

Other Large Folders Worth Checking After the Move

Photos is usually the biggest single folder under your home directory, but it is rarely the only one. After the move you may still find large caches in locations like ~/Library/Caches, developer artefacts in ~/Library/Developer/Xcode/DerivedData, or application support data scattered across ~/Library/Application Support. A tool like Crumb can audit all of these at once and show what is safe before you delete. To understand what else might be lurking, see the guide on how to free up space on a Mac.

Frequently Overlooked Pitfalls

• Multiple libraries: If you have created additional libraries in Photos over the years, each one is a separate .photoslibrary package and must be moved individually. Check ~/Pictures/ for any files with that extension.
• Time Machine exclusions: By default, Time Machine backs up external drives only if you explicitly include them. After the move, go to System Settings → General → Time Machine → Options and confirm your external drive is listed as a backup source, not excluded.
• Slow USB 2 or bus-powered hubs: A 200 GB library over USB 2 can take four or more hours to copy. Use a direct USB 3 or Thunderbolt connection for best results.
• APFS versus HFS+ on the external drive: APFS handles large numbers of small files efficiently and supports snapshots, making it the better choice for a Photos library on an external SSD. HFS+ (Mac OS Extended) is more compatible with older Macs or drives shared between systems.