How to Move Your Mac Photos Library to an External Drive
A Photos library can quietly grow to fill a Mac, and moving it to an external drive is a clean way to reclaim space. The golden rule is simple: never delete the original until the moved library opens perfectly and your backup is current.
Follow these steps
- Back up before you move anything. Make sure your Time Machine backup is current before touching the library. Moving a library is safe when done carefully, but a backup means a mistake is recoverable.
- Prepare an external drive formatted for Mac. Use a drive with enough free space for the whole library, formatted for Mac use. If the drive is new, macOS will offer to use it, but check that it has room before you start copying.
- Quit Photos completely. Close the Photos app fully before moving its library. Moving files while Photos is open can corrupt the library or leave it in two halves.
- Find your Photos library. In Finder, open your Pictures folder. The library is the file called Photos Library, and it contains all your photos, videos, and edits in one package. Do not open it and move photos out by hand.
- Copy, do not move, the library to the external drive. Drag the library to the external drive while holding Option, or copy and paste it, so the original stays put for now. Copying takes a while for a large library, so leave the Mac plugged in and undisturbed.
- Open the moved library from the external drive. Hold Option while opening Photos, choose the library on the external drive, and browse through it. Check recent photos, albums, and videos to confirm everything arrived intact.
- Only then set the new library as your system library and remove the old one. In Photos settings, confirm the drive library is your system library, use it normally for a while, and only then delete the original from your Mac, after confirming your backup also holds it.
What NOT to do
- Never delete the original library immediately after copying. Verify the moved library opens and shows your photos first.
- Do not move individual photos out of the library package by hand. Photos manages its own files, and hand-moving them breaks albums and edits.
- Do not store your only copy of the library on a drive you carry around unprotected. A lost drive is a lost library without a backup.
If the moved library opens perfectly and your backup is current, you have safely freed a large amount of space. Keep the external drive connected whenever you open Photos, or Photos may create a new empty library.