Photos Library on Mac: Backup, Merge, and Recover
I have rescued tens of thousands of photos from corrupted libraries. Here's how to never need rescuing.
Quick answer
A Mac Photos library is a single package file, normally in your Pictures folder. Back it up by including it in Time Machine and by keeping a second copy on an external drive. To merge libraries, open each one and export originals, then import into the library you're keeping — Photos cannot merge in place.
Your Photos library is a package — a folder pretending to be a file. It lives in Pictures by default. Right-click and Show Package Contents if you ever need to see inside, but otherwise leave it alone.
The library should be backed up by Time Machine automatically. Verify this. Open Time Machine, browse into Pictures, confirm you see your library snapshot. Don't assume.
If you have multiple libraries from old Macs, merging them is possible but tricky. There are paid tools like PowerPhotos that do it cleanly. The free path is to import one library into another inside Photos itself, but it's slow and easy to duplicate.
If a library is corrupted, hold Option and Command while opening Photos to access the Repair Library tool. It often works on the first try. If it doesn't, stop opening the library and call someone. Repeated failed opens make recovery harder.
Frequently asked
Where is the Photos library stored on a Mac?
By default at Pictures/Photos Library.photoslibrary. It's a package, so it looks like one file but contains the whole library.
How do I merge two Photos libraries?
Open the secondary library, select all, export unmodified originals to a folder, then switch to the main library and import that folder. There is no built-in merge.
Does iCloud Photos count as a backup?
No. It's a sync service — a deletion syncs everywhere. Keep a real backup in addition to iCloud.
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