Storing photos on an external hard drive with a Mac works two ways: you can move the whole Photos library to the drive, or keep your photos as regular files in folders on it. The first keeps the Photos app working the way you’re used to. The second suits camera files, RAW files and anyone who doesn’t live in the Photos app.
Either way, one rule matters more than the setup: an external hard drive should never hold the only copy of your photos.
Two ways to store photos on an external drive
| Move the Photos library | Keep photos as folders | |
|---|---|---|
| Best for | Photos you view and edit in the Photos app | Camera files, RAW files, client work, archives |
| What you see | The Photos app, same as before | Folders in Finder, named by year and event |
| Frees space on your Mac | Yes, once you delete the original library | Yes, once you remove the copies from your Mac |
| The catch | The drive has to be connected whenever you open Photos | You organize it yourself |
Option 1: Move your Photos library to the external drive
This is Apple’s way, and it’s the right one if your photos live in the Photos app.
Check the drive first. Apple says the drive has to be formatted APFS or Mac OS Extended (Journaled), and it can’t be the drive you use for Time Machine backups. Apple also advises against SD cards, USB flash drives, and anything shared over a network or synced to cloud storage, to avoid losing data.
Then move it:
- Quit the Photos app.
- In Finder, open the Pictures folder in your home folder. Choose Go > Home from the menu bar if you can’t find it.
- Drag Photos Library onto the external drive. A big library takes a while to copy.
- When the copy finishes, double-click Photos Library in its new place on the drive to open it.
- If you use iCloud Photos, set it as your System Photo Library in Photos settings.
- Once you’ve checked everything opened, drag the original Photos Library from the Pictures folder to the Trash and empty it. That’s the step that gets your storage back.
Keep the drive connected before you open Photos. If Photos can’t find the drive, it starts a new, empty library in the Pictures folder. Your photos are still on the drive. Connect it, hold the Option key while opening Photos, and choose the library on the drive.
If you get a permissions error during the move, select the drive in Finder, choose File > Get Info, and make sure Ignore ownership on this volume is checked.
Option 2: Keep your photos as folders on the drive
If you shoot on a camera, keep RAW files, or edit in something other than the Photos app, plain folders on the drive are simpler and last longer. There’s no library to break.
A folder structure that holds up for years:
- One folder per year, and inside it one folder per event:
2024/2024-07 Lake trip,2024/2024-12 Holidays. - Date first in folder names, so everything sorts in time order.
- Originals stay originals. Put edited exports in a separate folder, such as
2024-07 Lake trip/Edits, so you never overwrite what came off the card. - Import once. Copy the card to the drive, check the copy, then format the card in the camera. Importing the same card twice is where most duplicate photos come from.
One copy isn’t storage
Every external hard drive fails eventually, and portable ones get dropped, lost and left in bags. The safest setup is more than one copy in more than one place:
- The working copy, on your Mac or your main external drive.
- A second copy on a different drive.
- One copy away from home, whether that’s cloud storage or a drive kept somewhere else.
Open a few photos from each backup now and then. A backup you’ve never checked is a guess.
SSD or hard drive?
An external SSD is faster and handles being carried around better, which suits a library you open every day. A traditional external hard drive costs less for the same space, which suits an archive or a backup. Plenty of people use an SSD for this year and hard drives for everything older.
The problem that shows up a year later: duplicates across drives
A two-drive system turns into a mess in a predictable way. You copy your photos to a drive “just in case”. A year later you copy them again, plus the new ones. Then a second drive gets a copy too. Now every photo from 2019 exists five times, and nobody’s sure which drive has the complete set.
Two habits prevent it:
- One working copy. Every other drive is a backup of that one, not a place you add to separately.
- Deduplicate before you consolidate. When you’re merging drives, find the duplicates first, then move what’s left.
How to find and delete duplicate photos on a Mac covers the free ways to find copies, including photos outside the Photos app.
Using SupaDupa with photo drives
SupaDupa is a Mac app built for people with more than one drive.
- It remembers every drive you connect. Search keeps working on a drive after you unplug it, so you can check what’s on it without digging it out of the drawer.
- It finds exact duplicates on a drive for free, with no file limit, and moves the copies you choose to the macOS Trash.
- It can tag photos by what’s in them, so a search for “kayaking 2019” finds them a year later. Tagging is free on one folder you pick and part of Pro everywhere else.
- Similar photos are a Pro feature: the same shot exported twice at different sizes. It reads JPEG and PNG, not HEIC or RAW, though exact copies of those are still found.
- The free version covers every drive you plug in. Pro is $49, once, for the AI features on every folder.
Leave the Photos library itself to the Photos app, and point SupaDupa at your photo folders and drives.
Before you move a single photo
- Back up first, even before the move. A copy that’s still in progress isn’t a copy yet.
- Check the format. APFS or Mac OS Extended (Journaled) for a Photos library.
- Don’t use the Time Machine drive. Apple says the library can’t live there.
- Open a few photos from the new location before you delete anything from your Mac.
Once the photos have a home, how to organize digital photos covers sorting them without touching each one twice.
Pick the setup that matches how you use your photos, move them once, and make the second copy the same day.