When your Mac storage is full, open System Settings › General › Storage to see what takes up space. Turn on the recommendations, then click ⓘ next to a category like Documents or Applications to delete large files, old downloads and apps you don't use. Free Up Space in MrFixable finds caches that Storage doesn't list.

A full disk makes a Mac slow, stops macOS updates from installing and can make apps fail to save. The fix starts with finding out where the space went, and macOS can show you.

How do I see what's taking up space on my Mac?

Open System Settings › General › Storage. The bar at the top shows how much space each kind of file uses, such as Applications, Documents, Photos and System Data, and how much is free. Below it, each category is listed with its size, and most have an ⓘ button that shows the files inside.

Choose Apple menu › System Settings.
Click General in the sidebar, then click Storage.
Wait for the bar at the top to finish calculating. It shows how much space each kind of file uses and how much is free.
Look at the list below the bar. Each category shows its size, and most have an ⓘ button that opens the files inside.

The categories you'll see depend on what's on your Mac. The ones that usually matter most:

Applications: the apps you installed, not the ones that come with macOS.
Documents: files in your home folder that aren't in another category, including your Downloads.
Photos, Messages and Mail: your photo library, message attachments and mail.
iOS Files: backups and software updates of iPhones and iPads you connected to this Mac.
Trash: what you deleted but haven't emptied yet.
macOS: the system itself, which you can't make smaller.
System Data: everything else, such as caches, logs and temporary files. It has no ⓘ button. See how to clear System Data.

How do I free up space on a Mac?

Delete what you don't need from the biggest categories in System Settings › General › Storage: large files, old downloads, unused apps and old iPhone backups. Then empty the Trash. The recommendations at the top of Storage can also keep files in iCloud and empty the Trash for you automatically. Start with whatever is largest on your Mac.

Use the recommendations at the top of Storage. Store in iCloud keeps your Desktop, Documents and photos in iCloud and only recent files on the Mac. Optimize Storage removes Apple TV movies and shows you've already watched. Empty Trash automatically deletes items that have been in the Trash for more than 30 days.
Find large files. Click ⓘ next to Documents, then click Large Files. Select files you don't need and click Delete. Use Show in Finder first if you're not sure what a file is.
Clear old downloads. In the same window, click Downloads. Installers (.dmg and .pkg files) and zip files you've already opened are usually safe to delete.
Delete apps you don't use. Click ⓘ next to Applications, select an app and click Delete.
Remove old device backups. Click ⓘ next to iOS Files and delete backups of iPhones or iPads you no longer have. Keep the latest backup of a device you still use.
Clean up message attachments. Click ⓘ next to Messages to see large attachments and delete the ones you don't need.
Empty the Trash. Choose Finder › Empty Trash. Deleted files keep taking up space until you do.

To see which folders are biggest, click ⓘ next to Documents and choose File Browser. It shows how much space each folder uses.

Why does my Mac storage keep filling up?

Mostly because of files that grow quietly in the background. App caches get bigger over time, downloads pile up, iPhone backups can be large and Messages keeps every photo and video you receive. Time Machine also keeps local snapshots for about 24 hours, but your Mac counts that space as available and removes them when it needs room.

If your storage keeps filling up, check Storage once a month, turn on Empty Trash automatically, and clear caches now and then.

Free the hidden space in one step

Storage settings don't show app caches or the caches of developer tools. Free Up Space in MrFixable does. It shows how much is free on your Mac, then lists:

App caches, with the biggest ones named. macOS's own caches and the caches of apps that are open are skipped.
Xcode build files, old iPhone and Watch debug files, the npm download cache and the Gradle cache, if you have them.
Downloads older than 30 days and the Trash, unticked to begin with.
Simulator apps and data, if you have Xcode, also unticked.

Each one shows its size. The safe ones start ticked: tick or untick the rest, then click Free Up Space. Caches and build files are deleted for good, because they're made again when needed, and old downloads go to the Trash so you can still get them back.

To remove apps you don't use together with the files they leave in your Library folder, use App Uninstaller.

Questions

Why is my Mac storage full?

Usually large files you've forgotten about: downloads, videos, old iPhone backups, message attachments and the Trash. Caches and temporary files add more. Open System Settings › General › Storage to see which category is biggest, then click its ⓘ button to see the files inside and delete what you don't need.

What should I do when my Mac storage is full?

Empty the Trash first, because it's the quickest win. Then open System Settings › General › Storage, click ⓘ next to Documents and delete large files and old downloads you don't need. Delete apps you don't use, remove old iPhone backups and restart your Mac to clear temporary files.

How do I free up space on a Mac without deleting files?

Turn on Store in iCloud in System Settings › General › Storage. Your Desktop, Documents and photos are kept in iCloud, and only recent files stay on your Mac when space is low. You need enough iCloud storage for this. You can also move large files, like videos, to an external drive.

Mac storage full? See what takes up space and free it up