Is Your Photos Library Too Big? Here’s How to Move It to an External Hard Drive

If you don’t know what the picture at the beginning of this blog is, it’s likely you are younger than 40?! Those are film rolls that we older folks used to use to shoot and store photographs. The maximum number of shots you could take was 36 and when the roll was finished, you’d have to go through the hassle of having the film processed. Flash forward to today’s digital media cards that allow us to shoot thousands of photographs with virtually no concern for using up the space on the card. While this certainly takes the concern out of using up the available film, the end result is that we have tens of thousands more photos to view, organize, and keep safe. The following solutions can help us to manage our ever-increasing digital life and deal with a hard drive that is hitting its capacity for photo storage.

If your Photos library has grown to the point where your hard drive is nearly full, it might be time to think about offloading it to an external hard drive. (Don’t put it on a drive that you’re using as a Time Machine destination because there could be permissions conflicts, and note that Apple doesn’t recommend storing a Photos library on a drive shared over a network.)

Consider Swapping Full Resolution Images for Smaller Images 

Before we explain how to offload your photos, we want to mention another way of reducing the Photos footprint on your drive. If you’re using iCloud Photos (previously called iCloud Photo Library) to sync photos and videos between your devices, the originals are all stored in iCloud. In Photos > Preferences > iCloud, you can enable Optimize Mac Storage, which swaps the full-resolution images for smaller versions, saving a boatload of space. In other words, this allows the thumbnail of your photo to display, but keeps the larger full-sized image in the cloud. However, you may find Photos somewhat slower to use, as it has to download full-resolution versions of images you work with, and you won’t have a local backup of the original images.  It also means you will need to use an internet connection to edit or view the full-sized image, which could prove to be a hassle sometimes. For many people this is a fine solution and you needn’t try to further solve the space issue. So keeping the large version on the Cloud is an option, but it has tradeoffs.


Offload Entire Library to External Hard Drive 

For most people with burgeoning Photos libraries, a better approach is to offload the entire library to an external hard drive. This approach comes with tradeoffs too; accessing images from a hard drive is slower than getting them from an internal solid state drive, and you have to figure out how you’re going to back up that drive as well. Plus, this solution adds some layers of complexity to accessing your photos:  the drive has to be available, connected, and turned on (so you have to listen to it) for you to use Photos at all, which might be especially annoying if you regularly work remotely on a notebook Mac. 

To move your Photos library to an external drive, follow these steps:

A word of caution here: Be certain you have a current backup of the library before you copy it to the external drive and before you delete the photo library on your computer’s start up to free up the space.

1.If it’s running, quit Photos.

2.In the Finder, drag Photos Library, which is stored in your Pictures folder by default, to the external drive. A few answers to common questions:

  • Where on the external drive should I put it? It doesn’t matter, but we recommend putting it at the top level so you are less likely to lose track of it in the future.

  • I got an error—what should I do? If you see an error telling you that you don’t have permission to copy to that drive, select the drive’s icon in the Finder and choose File > Get Info to open the Info window. If necessary click the triangle next to Sharing & Permissions, and make sure “Ignore ownership on this volume” is selected. If it’s not, click the lock icon, enter an administrator name and password, and select the checkbox. If you get an error and don’t feel confident handling it, please come see us at the GeekBar.

  • How long will it take to copy? Quite some time, depending on how many photos you have. It’s best to do overnight or when you don’t need to use Photos.

3. When it’s done copying, double-click the new Photos Library icon on the external hard drive to launch Photos and set it to open that new copy on future launches.

4. If you use iCloud Photos, designate this new library as the System Photo Library by choosing Photos > Preferences > General and clicking the “Use as System Photo Library” button.

5. Scroll through your photo collection and make sure all your photos are present—double-click a few of them to spot check that the actual images open properly.


Obviously, your original Photos library is still taking up space on your SSD, but it’s best to use the new version for a little while before deleting the old one, just in case. When you’re ready to do that, drag it from the Pictures folder to the trash and choose Finder > Empty Trash to reclaim the space.

If all this makes your head spin you are not alone.  Each person’s photo habits, photo library size and devices used (computer, iPhone, iPad) will be different. It makes sense to have a conversation with someone, perhaps at the GeekBar or during an in-home visit, about what the best method is for you. One thought is to only keep the last couple of years on all your devices or in the main library. You could also start a new library at the beginning of each year or two to minimize size and number.  Which scheme to choose is personal. Some thought needs to be given before doing anything with some of our most precious keepsakes. GeekHampton is here to help. We can assist with learning the pros and cons of utilizing iCloud photos or external hard drives.