Prepare your external drive
You can store your library on an external storage device, such as a USB or Thunderbolt drive formatted as APFS or Mac OS Extended (Journaled). However, you can't move your library to a disk that's used for Time Machine backups.
To prevent data loss, Apple recommends not storing photo libraries on external storage devices, such as SD cards and USB flash drives, or drives that are shared on a network.
Move your Photos library to an external storage device
- Quit Photos.
- In the Finder, go to the external drive where you want to store your library.
- In another Finder window, find your Photos Library. It's stored in the Pictures folder located in /Users/[user name]/Pictures by default.
- Drag Photos Library to its new location on the external drive. If you see an error, select your external drive's icon in the Finder, then choose File > Get Info. If the information under Sharing & Permissions isn't visible, click the triangle , then make sure the "Ignore ownership on this volume" box is selected. If it's not selected, click the lock button to unlock it, enter an administrator name and password, then tick the box box.*
- After the move has finished, double-click Photos Library in its new location to open it.
- If you use iCloud Photo Library, designate this library as the System Photo Library.
Make sure the drive is turned on and available to your Mac before opening Photos. If Photos can't find your drive, it will stop using the Photos Library stored there.
Delete original library to save space
After you've opened your library from its new location and made sure it's working as expected, you can delete the library from its original location.
In a Finder window, go back to your Pictures folder (or whichever folder you copied your library from) and move Photos Library to the bin. Then choose Finder > Empty Bin to delete the library and reclaim disk space.
Open another Photos library
If you have multiple libraries, here's how to open a different one:
- Quit Photos.
- Press and hold the Option key while you open Photos.
- Select the library you want to open, then click Choose Library.
Photos will use this library until you open a different one.
If you encounter a permissions issue with your library, you may be able to resolve it by using the Photos library repair tool.
* If the volume isn't formatted as APFS or Mac OS Extended (Journaled), or has been used for Time Machine backups but hasn't been erased, this tickbox will either not be present, or you won't be able to tick it after unlocking. Erase the drive for this option to be available.