Help · Mac storage
How to move your Photos library to an external drive.
The Photos library is often the biggest single thing on a Mac. Moving it to an external drive frees all that space, and Photos works just as before while the drive is connected. Do it the way Apple describes; a library moved the wrong way can become unreadable.
Have a backup before you start, and keep the original library until you've checked the moved one. If you use iCloud Photos, your photos are also in iCloud, but don't rely on that alone.
1. Prepare the drive
- Format: APFS or Mac OS Extended (Journaled). Not exFAT. Check with File › Get Info on the drive in Finder.
- Not your Time Machine drive, and preferably not an SD card, USB stick, network drive or a cloud-synced folder.
- Ownership: select the drive in Finder, choose File › Get Info, open Sharing & Permissions, click the lock if needed, and make sure Ignore ownership on this volume is ticked, as Apple's guide says.
- Room: the drive needs more free space than the library's size (select the library and use Get Info).
2. Move it
- Quit Photos.
- In Finder choose Go › Home and open Pictures.
- Drag Photos Library to the external drive. It copies, which can take a long time for a big library.
- When it's done, double-click the library on the drive to open it in Photos. (Or hold ⌥ while opening Photos and choose it.)
- If you use iCloud Photos, or want other apps to see your photos, choose Photos › Settings › General and click Use as System Photo Library.
3. Check, then remove the old copy
- Browse the moved library for a few days: open albums, recent photos and some old ones, and play a video.
- When you're sure it's complete, move the old Photos Library in your Pictures folder to the Trash, then empty the Trash to get the space back. This is permanent, so be certain the new one works.
Living with it
- Connect the drive before opening Photos. If Photos can't find the library, it offers to make a new, empty one. Quit instead and connect the drive.
- Back up the drive. Time Machine can include it: remove it from the excluded list in Time Machine's options.
- Prefer not to move it? With iCloud Photos, Photos › Settings › iCloud › Optimise Mac Storage keeps smaller versions on your Mac and full-resolution originals in iCloud.
See how big your Photos library really is.
Pangalin Space Manager measures your Photos library alongside everything else, and gives Apple's own steps for it, with an Open Photos button and a link to Apple's guide. It never moves or prunes the library by hand, because only Photos may safely change it. Its guided move refuses drives Photos can't use, and checks that “Ignore ownership on this volume” is selected, as Apple asks.
Free to scan · first 5 GB freed free, then $25 a year · 14-day full refund · Notarised by Apple