The fastest way: drag and drop to a folder

Plug your external hard drive into your Mac's USB or Thunderbolt port. Your Mac will mount it as a disk on the desktop or in Finder's sidebar. Open Finder, navigate to your Photos library or the folder where your image files live, select the photos you want to move, and drag them onto a folder on the external drive. This works for most people and takes seconds.

If you're moving your entire Photos library (not just individual photos), the process is different — see the section below on moving the full library. For loose image files scattered in folders, drag-and-drop is the simplest route.

One thing to know: dragging copies the files by default. If you want to move them and remove them from your Mac to free up space, hold down Command and Option while dragging, or use cut and paste instead (Command-X to cut, Command-V to paste).

Key Takeaways

  • Drag and drop works for individual photos or folders of images — just select what you want, drag it to a folder on the external drive, and it copies over.
  • Moving your entire Photos library requires closing the app first, then dragging the Photos Library file itself to the external drive, then telling Photos where to find it.
  • Your external drive must be formatted as Mac OS Extended or APFS to work smoothly with a Mac; if it's formatted for Windows, you can still use it but may run into permission issues.
  • After copying photos, verify they arrived by opening the external drive folder and spot-checking a few files before deleting anything from your Mac.
  • If you use iCloud Photos, your originals may be stored in the cloud rather than on your Mac, and you'll need to read them first before moving them to an external drive.

Moving your entire Photos library to external storage

If you want to move the whole Photos app library (not just individual photos), the process is more involved because Photos needs to know where the library moved to. First, quit the Photos app completely. Open Finder and navigate to your home folder, then to Library > Photos. You'll see a file called "Photos Library.photoslibrary" — this is your entire library, including all photos, videos, and metadata.

Drag this file to a folder on your external drive. Depending on how many photos you have, this can take anywhere from a few minutes to an hour. Once it finishes, open Photos again. The app will ask you to locate your library. Click "Other Library" and navigate to the Photos Library file you just moved on the external drive. Select it and click "Choose." Photos will now use that library as its default.

After this, your external drive must be connected whenever you want to use Photos. If you disconnect it, Photos won't open. This is why most people keep individual photos on their Mac and use the external drive as a backup, rather than moving the entire library.

Checking your external drive's format before you start

Your external drive's format matters. Macs work best with drives formatted as Mac OS Extended (also called HFS+) or APFS. If your drive came formatted for Windows (NTFS or exFAT), you can still copy files to it, but you may run into permission problems later, especially if you're moving the entire Photos library.

To check the format, plug in the drive, right-click it in Finder, and select "Get Info." Look for the "Format" line. If it says NTFS or exFAT and you plan to move your Photos library, you should reformat it first. This erases everything on the drive, so back up any files already on it. Right-click the drive, select "Erase," choose "Mac OS Extended" or "APFS" as the format, give it a name, and click "Erase." Once that's done, you can copy your photos over.

If you're only copying individual photos and don't mind the occasional permission warning, you can skip reformatting. But if you're moving your entire Photos library, reformatting first will save you headaches.

Handling iCloud Photos and downloaded originals

If you use iCloud Photos, your Mac may not actually store full-resolution originals locally. Instead, it stores thumbnails and lower-resolution versions, with the full files in iCloud. When you try to copy these to an external drive, you're copying the lower-resolution versions, not the originals.

To move your full-resolution photos, you need to read them first. Open Photos, go to the menu bar, click "Photos" > "Settings," then go to the "iCloud" tab. Look for the option that says "read originals to this Mac" or similar (the exact wording varies by macOS version). Turn this on and wait for your Mac to read all your originals from iCloud. This can take hours or days depending on how many photos you have and your internet speed.

Once the read is complete, you can drag and drop the photos to your external drive as normal. The files will now be full-resolution originals rather than cloud-optimized versions.

Verifying the copy worked before deleting originals

After copying photos to your external drive, spot-check a few files before you delete anything from your Mac. Open the external drive in Finder, navigate to the folder where you copied the photos, and open a few image files. Make sure they look correct and aren't corrupted. If you moved your entire Photos library, open Photos with the external drive connected and browse through a few albums to confirm everything is there.

This step takes five minutes and can save you from accidentally losing photos. Once you've confirmed the copies are good, you can delete the originals from your Mac if you want to free up space. If you're keeping both copies (one on your Mac and one on the external drive), you don't need to delete anything — you now have a backup.

Using Time Machine as an alternative to manual copying

If you want your external drive to back up your entire Mac automatically rather than just copying photos manually, you can use Time Machine. Plug in the external drive, open System Preferences (or System Settings on newer Macs), go to Time Machine, and click "Select Backup Disk." Choose your external drive and click "Use Disk." Time Machine will now back up your entire Mac, including all photos, every hour.

This is different from manually copying photos because Time Machine creates versioned backups — you can restore your Mac to any point in time over the past weeks or months. It's slower than drag-and-drop but requires no ongoing effort. If you're mainly concerned with having a backup in case something goes wrong, Time Machine is often easier than managing manual copies.

Frequently Asked Questions

Can I move photos to an external drive and still see them in Photos?

Only if you move your entire Photos library to the external drive and keep the drive connected. If you just drag individual photos to the external drive, they'll no longer appear in the Photos app on your Mac. You'll need to open them directly from the external drive using Finder or another image viewer.

What happens if I unplug the external drive while Photos is open?

If your Photos library is on the external drive and you unplug it, Photos will freeze or close. Always quit Photos before unplugging the drive. If you accidentally unplug it while Photos is running, plug it back in and restart the app.

Do I need to erase my external drive before copying photos to it?

No, unless it's formatted for Windows and you're moving your entire Photos library. You can copy photos to a drive that already has other files on it. Just make sure the drive has enough free space for the photos you're copying.

How long does it take to copy a large photo library?

It depends on the size of your library and the speed of your drive connection. A few thousand photos might take 10 to 30 minutes over USB 3. Larger libraries or older USB 2 connections can take hours. Thunderbolt connections are faster. You can check progress in Finder — it will show you how much time is remaining.

Can I copy photos to an external drive on Windows and then use them on my Mac?

Yes, as long as the drive is readable by both systems. exFAT format works on both Mac and Windows. You can copy photos to an exFAT drive on Windows and then plug it into your Mac to access them. However, if you're moving your entire Photos library, stick with Mac OS Extended or APFS format for better compatibility with Photos.