How to free up space on your Mac by moving your Photos library to an external drive

Your Photos library holds all your photos, albums, slideshows, and print projects. If your library is large, and you want to free up storage space on your Mac, you can move your library to an external drive.

Before you start, be sure to back up your library.

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). Note that you can’t move your library to a disk that’s used for Time Machine backups. To prevent data loss, Apple doesn’t recommend storing photo libraries on external storage devices like SD cards and USB flash drives, or drives that are shared on a network.

Move your Photos library to an external storage device

  1. Quit Photos.

  2. In the Finder, go to the external drive where you want to store your library.

  3. In another Finder window, find your library. The default location is Users > [username] > Pictures, and it’s named Photos Library.

  4. Drag your 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 button, then make sure the “Ignore ownership on this volume” checkbox is selected. If it’s not selected, click lock icon to unlock it, enter an administrator name and password, then select the checkbox. Note that if the volume isn’t formatted APFS or Mac OS Extended (Journaled), or has been used for Time Machine backups but hasn’t been erased, this checkbox will either not be present, or won’t be selectable after unlocking. Erase and reformat the drive for this option to be available.

  5. After the move is finished, double-click Photos Library in its new location to open it.

  6. If you use iCloud Photo Library, designate this library as the System Photo Library.

Delete the original library to save space on your Mac

After you open your library from its new location and make sure that it works 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 trash. Then choose Finder > Empty Trash 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:
1. Quit Photos.
2. Press and hold the Option key while you open Photos.
3. Select the library that you want to open, then click Choose Library.

Photos uses this library until you open a different one.

If you have a permissions issue with your library, you might be able to resolve the issue by using the Photos library repair tool.

Enjoy your Mac’s extra storage space! (And back up that external drive containing your Photos library regularly.)


  1. What a horrible workaround for Apple being notoriously stingy on space and/or overcharging. For example on a New MacBook Pro going from 512 GB space to 2TB space costs a whopping $1200. Ridiculous and forces people to come up with stupid workarounds like external storage.

    1. Large fast SSDs are expensive. Just looking at OWC or Macsales and a recent vintage MBP, 2015, a 2TB SSD upgrade costs $935.

      As for external storage, the people who actually need 2TB, are usually also the types who use external storage, as primary or backup storage to begin with.

      1. SSD prices have been expensive for quite awhile, but we do need to differentiate between Apple-compatible ones and Industry commodity ones.

        For example, a 2TB M.2 stick (SAMSUNG 860 EVO Series M.2 2280) at Newegg currently goes for $300.

        As such, the other $600 to make it MBP compatible is because Apple chose to not follow existing industry standards. Granted, the bandwidth that Apple gets is better, but is it worth ~3x more? Maybe not.

        FWIW, another interesting insight & perspective here is that the users who actually need lots of TB were historically well served by the classic “Cheese Grater” Mac Pro desktop, which Apple has chosen to no longer offer in their product line. Time will tell if the rumored 2019 ‘modular’ MP will actually be a decent “with storage” configurable product, or something else.

  2. Wise Mac owners have held onto proper workstations, where internal drive bays could host separate iTunes libraries, Time Machine backups, working files server, and more — all internally, all user upgradeable without a solder gun and exotic tools.

    Man those were good days.

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