How to Move Your Photos Library to an External Drive (Mac)

MacCleaner · 2026-08-05 · 6 min read

Short answer

To move a Photos library: quit Photos, copy the .photoslibrary file to your external SSD (don't move it until the copy completes), then hold Option while opening Photos and choose the library in its new location. Set it as the System Photo Library if you use iCloud. Keep the drive connected — and keep a backup, since a single external copy is not a backup.

The safe procedure

Quit Photos.
Copy (don't move) Photos Library.photoslibrary from ~/Pictures to the external SSD.
Hold Option while opening Photos → Other Library → choose the copy on the SSD.
Verify everything is there, then in Settings → General mark it as System Photo Library if you use iCloud Photos.
Only after verifying, delete the original to reclaim space — and empty the Trash.

The pitfalls

Use a fast SSD, formatted APFS. Avoid network drives and most USB flash sticks — Photos misbehaves on them. And remember: one copy on one external drive is not a backup. Keep Time Machine or a second copy.

Also worth knowing: macOS can invalidate file handles to external volumes during sleep, which is why some people see odd Photos behaviour on externals. Keeping the drive awake while Photos is open avoids most of it.

The alternative: don't move, offload

If you use iCloud Photos, Optimise Mac Storage keeps full-resolution originals in the cloud and light copies locally — often simpler than managing an external drive. Details in Photos library storage.

To see what else is taking space alongside Photos, MacCleaner's read-only scan lays it out with real sizes.

Frequently asked questions

Can I move my Photos library to an external drive?

Yes. Quit Photos, copy the .photoslibrary to a fast APFS-formatted SSD, then hold Option while opening Photos and select the library in its new location.

Will moving my Photos library break iCloud Photos?

No, but you must mark the moved library as the System Photo Library in Photos settings, and keep the drive connected for syncing to work.

Is an external drive a backup for my photos?

No. A single copy on one drive is not a backup — keep Time Machine or a second copy as well.

Reclaim the space in two taps

MacCleaner scans read-only, shows every file before anything is touched, marks the safe groups, and lets you choose Trash or permanent. Free for up to 500 MB of cleanup a day.

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