You may have three Photos libraries without knowing it. How to find them all
Old libraries from upgrades, copies from another Mac, and a library on an external drive. How to find every Photos library, see which is active, and what to keep.
Photos only shows one library at a time, the one it opened last. Others stay on disk, full size, until you find them: an old library from an upgrade, a copy restored from a backup, one copied across from another Mac.
Find them
mdfind -name .photoslibrary
find ~ /Volumes -maxdepth 4 -name '*.photoslibrary' -exec du -sh {} + 2>/dev/nullTerminal needs Full Disk Access to measure them. Older libraries may end in .photolibrary or be named iPhoto Library.
See which one is active
Hold Option while opening Photos. It lists the libraries it knows about. The System Photo Library, the one iCloud syncs, is marked in Photos, Settings, General.
Decide what to keep
| Library | Usually |
|---|---|
| The System Photo Library | Keep |
| A copy with the same photos | Remove once you have checked |
| An old library with photos not in the current one | Export those, import them, then remove |
| An iPhoto library from an upgrade | See old iPhoto library |
Photos has no merge feature. To combine libraries, open the old one, export the originals with File, Export, Export Unmodified Original, then import them into the current library, which warns about duplicates.
Common questions
How do I find all Photos libraries on my Mac?
Run mdfind -name .photoslibrary in Terminal, or hold Option while opening Photos to see the libraries it knows.
How do I know which Photos library is the System Photo Library?
Open Photos, then Settings, General. The current library shows whether it is the System Photo Library.
Can I merge two Photos libraries?
Not directly. Export originals from one and import them into the other, which checks for duplicates.