What is taking up space on my Mac? How to see it in 2 minutes

Part of: Mac storage full? Find what is using it and free up space safely (Storage full)

You can see what is using your Mac’s space in about two minutes. Check the Storage settings for the big picture, then run one read-only command to see your largest folders. Neither step changes any file.

Step 1: open the Storage settings

Choose Apple menu › System Settings › General › Storage. You will see a bar split into categories such as Applications, Documents and System Data, and the amount of space available.

This view is quick, but it is vague. A category like System Data does not tell you which folder is big. It is a good first look and a poor final answer.

Step 2: read your biggest folders

Open Terminal and run:

du -sh ~/* | sort -h

Here is what it does. du -sh prints the size of each item in your home folder in a readable form (for example 4G). sort -h puts the biggest at the bottom. The command only reads. It can take a minute on a large disk, so wait for it to finish.

Two limits to know about:

• ~/* skips hidden folders, the ones starting with a dot.
• Terminal may not be allowed to read some protected folders. Those can show as errors or smaller than they are.

Then look one level deeper in the biggest folder. Library is often large, so try:

du -h -d 1 ~/Library | sort -h

The last lines show which subfolders are largest, such as Application Support, Caches or Containers. You now know where to look.

The usual top five

These are the places that most often hold the space:

1. System Data. Caches, logs, snapshots and support files. See Mac storage full but no files? for why it can look bigger than the files you can see.
2. Library caches. Copies apps can rebuild. Library Caches: what is safe to delete.
3. iPhone backups. Each can be many gigabytes. iPhone backups on your Mac.
4. Downloads. Old installers and files you forgot. Clean up the Downloads folder.
5. Developer tools. Xcode and similar tools leave a lot behind. Clean up Xcode.

Why the numbers differ between tools

You may find that Finder, Storage settings and Terminal give different sizes for the same thing. This is normal, and it has three common causes:

• Allocated and logical size. A file can claim to be large but use less on disk, or share data with another file. Tools that add up the claimed sizes overstate the space.
• Purgeable space. macOS counts some space as available even though it is in use by data it can remove when needed.
• Rounding. Some tools use 1000 bytes per kilobyte and others use 1024.

None of these mean something is broken.

A worked example of reading the output

Say the last lines of the first command show a Library folder far larger than everything else. That tells you to go one level deeper, so you run the second command and see which subfolder is biggest. If it is Caches, the next step is to read about caches. If it is Application Support, the next step is to find out which app owns the biggest folder, since the folder name usually names the app. If it is Containers, the data belongs to an app you may still use. Each step narrows the search without removing anything.

The same method works for Downloads, Movies and Documents. Look at the total, then the biggest item inside, then decide. Nothing in this process needs you to delete a thing until you know exactly what it is. If you do decide to remove something, move it to the Trash first and empty it later, once you are sure nothing is missing.

You can also repeat the check from time to time. A quick look every few months shows what is growing, and what grows is usually what fills the disk.

Reading it all in one place

DiskJoy is our product. It scans the folders you allow and groups what it finds by category, counting each block of disk once, so shared data is not added up twice. A scan only reads file sizes and dates and changes nothing. DiskJoy is pre-alpha and cleanup is not available yet, so it shows you where the space is and you decide what to do. Download DiskJoy for Mac to try a scan.

What to do next

Once you know where the space is, the plan is simple. Start with the biggest item you are sure about. The complete guide to freeing up space on a Mac lists safe options in order. Remember that the Trash does not free space until you empty it.