Optimized Storage in macOS Sierra and later* can save space by storing your content in iCloud and making it available on demand. When storage space is needed, files, photos, movies, email attachments, and other files that you seldom use are stored in iCloud automatically. Each file stays right where you last saved it, and downloads when you open it. Files that you’ve used recently remain on your Mac, along with optimized versions of your photos.

* If you haven't yet upgraded to macOS Sierra or later, learn about other ways to free up storage space.

Sep 24, 2018 — Managing a huge gallery and organizing photos is a tricky business, even if you’re generally tidy, so it’s always a good idea to use some help. Especially when there’s software out there designed specifically to deal with an overload of pictures. The only trouble with professional photo organizing software is that, much like any photo equipment, it’s painfully expensive.

Find out how much storage is available on your Mac

Choose Apple menu  > About This Mac, then click Storage. This is an overview of available storage space on your Mac, as well as the space used by different categories of files:

Click the Manage button to open the Storage Management window, pictured below. (The Manage button is available only in macOS Sierra or later.)

Manage storage on your Mac

The Storage Management window offers recommendations for optimizing your storage. If some recommendations are already turned on, you will see fewer recommendations.

Store in iCloud

Click the Store in iCloud button, then choose from these options:

• Desktop and Documents. Store all files from these two locations in iCloud Drive. When storage space is needed, only the files you recently opened are kept on your Mac, so that you can easily work offline. Files stored only in iCloud show a download icon , which you can double-click to download the original file. Learn more about this feature.
  
• Photos. Store all original, full-resolution photos and videos in iCloud Photos. When storage space is needed, only space-saving (optimized) versions of photos are kept on your Mac. To download the original photo or video, just open it.
  
• Messages. Store all messages and attachments in iCloud. When storage space is needed, only the messages and attachments you recently opened are kept on your Mac. Learn more about Messages in iCloud.

Storing files in iCloud uses the storage space in your iCloud storage plan. If you reach or exceed your iCloud storage limit, you can either buy more iCloud storage or make more iCloud storage available. iCloud storage starts at 50GB for $0.99 (USD) a month, and you can purchase additional storage directly from your Apple device. Learn more about prices in your region.

Optimize Storage

Click the Optimize button, then choose from these options.

• Automatically remove watched movies and TV shows. When storage space is needed, movies or TV shows that you purchased from the iTunes Store and already watched are removed from your Mac. Click the download icon next to a movie or TV show to download it again.
  
• Download only recent attachments. Mail automatically downloads only the attachments that you recently received. You can manually download any attachments at any time by opening the email or attachment, or saving the attachment to your Mac.
  
• Don't automatically download attachments. Mail downloads an attachment only when you open the email or attachment, or save the attachment to your Mac.

Optimizing storage for movies, TV shows, and email attachments doesn't require iCloud storage space.

Empty Trash Automatically

Empty Trash Automatically permanently deletes files that have been in the Trash for more than 30 days.

Reduce Clutter

Reduce Clutter helps you to identify large files and files you might no longer need. Click the Review Files button, then choose any of the file categories in the sidebar, such as Applications, Documents, Music Creation, or Trash.

You can delete the files in some categories directly from this window. Other categories show the total storage space used by the files in each app. You can then open the app and decide whether to delete files from within it.

Learn how to redownload apps, music, movies, TV shows, and books.

Where to find the settings for each feature

The button for each recommendation in the Storage Management window affects one or more settings in other apps. You can also control those settings directly within each app.

• If you're using macOS Catalina, choose Apple menu  > System Preferences, click Apple ID, then select iCloud in the sidebar: Store in iCloud turns on the Optimize Mac Storage setting on the right. Then click Options next to iCloud Drive: Store in iCloud turns on the Desktop & Documents Folders setting. To turn off iCloud Drive entirely, deselect iCloud Drive.
  In macOS Mojave or earlier, choose Apple menu > System Preferences, click iCloud, then click Options next to iCloud Drive. Store in iCloud turns on the Desktop & Documents Folders and Optimize Mac Storage settings.
• In Photos, choose Photos > Preferences, then click iCloud. Store in iCloud selects iCloud Photos and Optimize Mac Storage.
• In Messages, choose Messages > Preferences, then click iMessage. Store in iCloud selects Enable Messages in iCloud.

• If you're using macOS Catalina, open the Apple TV app, choose TV > Preferences from the menu bar, then click Files. Optimize Storage selects “Automatically delete watched movies and TV shows.”
  In macOS Mojave or earlier, open iTunes, choose iTunes > Preferences from the menu bar, then click Advanced. Optimize Storage selects “Automatically delete watched movies and TV shows.”
• In Mail, choose Mail > Preferences from the menu bar, then click Accounts. In the Account Information section on the right, Optimize Storage sets the Download Attachments menu to either Recent or None.

Empty Trash Automatically: From the Finder, choose Finder > Preferences, then click Advanced. Empty Trash Automatically selects “Remove items from the Trash after 30 days.”

Other ways that macOS helps automatically save space

With macOS Sierra or later, your Mac automatically takes these additional steps to save storage space:

• Detects duplicate downloads in Safari, keeping only the most recent version of the download
• Reminds you to delete used app installers
• Removes old fonts, languages, and dictionaries that aren't being used
• Clears caches, logs, and other unnecessary data when storage space is needed

How to free up storage space manually

Even without using the Optimized Storage features of Sierra or later, you can take other steps to make more storage space available:

• Music, movies, and other media can use a lot of storage space. Learn how to delete music, movies, and TV shows from your device.
• Delete other files that you no longer need by moving them to the Trash, then emptying the Trash. The Downloads folder is good place to look for files that you might no longer need.
• Move files to an external storage device.
• Compress files.
• Delete unneeded email: In the Mail app, choose Mailbox > Erase Junk Mail. If you no longer need the email in your Trash mailbox, choose Mailbox > Erase Deleted Items.

Learn more

• When you duplicate a file on an APFS-formatted volume, that file doesn't use additional storage space on the volume. Deleting a duplicate file frees up only the space required by any data you might have added to the duplicate. If you no longer need any copies of the file, you can recover all of the storage space by deleting both the duplicate and the original file.
• If you're using a pro app and Optimize Mac Storage, learn how to make sure that your projects are always on your Mac and able to access their files.

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, turn on iCloud Photo Library and use Optimize Mac Storage, or move your library to an external drive.

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

Prepare your drive

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).¹ Find out how to check the format of your external storage device.

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 , then make sure the 'Ignore ownership on this volume' checkbox is selected. If it's not selected, click to unlock it, enter an administrator name and password, then select the checkbox.²
   
   
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 original library to save space

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.

Mac Photo Library Too Big Mac

Photos uses this library until you open a different one.

Learn more

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

1. You can't move your library to a disk that's used for Time Machine backups.

Apple Photos Library Too Big

2. 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.