Mac storage basics · Photos, music and video
Where is my Photos library stored on my Mac?
Short answer: By default it's the Photos Library package in your Pictures folder. Check its size with Command-I, and never edit its contents by hand.
By default it's a single package called Photos Library in your Pictures folder. To see its size, select it in Finder and press Command-I.
It looks like one file but contains your originals, edits, thumbnails and the database that ties them together. Don't open it and move or delete things inside by hand — that can damage the library. Use Photos itself to delete, export or move it as a whole.
If you have several libraries, hold Option while opening Photos to see and choose between them.