How to check what is taking up space on your Mac

1. Storage in System Settings

Open System Settings, General, Storage and give it a moment to finish calculating. Hover over the coloured bar to see what each segment is. Below it, each category has an info button. Click it to see the actual files or apps behind the number.

The most useful rows are Applications, which can be sorted by size and by when each app was last used, and Documents, which has a Large Files tab. iOS Files lists iPhone and iPad backups and installers. Messages lists attachments by size.

The limit: the categories only cover what macOS knows how to label. Everything else lands in System Data, which has no info button. On a Mac used for development or with many apps, that can be the largest row.

2. Folder sizes in Finder

Finder can show how large every folder is, which is the easiest way to walk down from your home folder to whatever is big.

• Open your home folder with Shift, Command and H, and switch to list view with Command and 2.
• Choose View, Show View Options, tick Calculate all sizes, and click the Size column to sort.
• Open the largest folder and repeat. To check a single item, select it and press Command and I.
• Press Shift, Command and Period to show hidden files and folders, such as .cache or .gradle. The Library folder is hidden too: choose Go while holding the Option key to open it.
• Choose View, Show Status Bar to see free space at the bottom of every Finder window.

3. Find large files with Finder search

Finder can search by size, which finds big files wherever they are hiding.

Open a Finder window and press Command and F. Set the search to This Mac. Click the first criteria menu, choose Other, find File Size in the list and select it. Then set it to is greater than and enter a size, for example 1 GB.

The results are individual files, not folders, so this is good for videos, disk images and archives. It will not reveal a folder made of many thousands of small files, which is what caches and developer folders usually are.

4. Terminal, for the places Finder hides

Two commands answer most questions. df shows the volume as a whole: its size, how much is used and how much is available. du adds up what a folder contains.

The first command below shows free space on your startup volume. The second lists everything in your home folder by size, hidden items included, largest last. To look deeper, replace the path with a folder from the result, such as ~/Library. Both commands only read. macOS may ask whether Terminal can access folders such as Documents and Downloads, and du cannot measure folders it is not allowed to read.

df -h /System/Volumes/Data
du -sh ~/* ~/.??* 2>/dev/null | sort -h | tail -25

Why the numbers do not add up

You will notice that Finder, System Settings and Terminal rarely agree. None of them is wrong. They count different things.

• Purgeable space. macOS can remove some data when it needs room, such as local Time Machine snapshots and files that are also stored in iCloud. Finder counts that space as available. Terminal counts it as used.
• Snapshots. A local snapshot keeps deleted files on disk until it expires, so free space may not rise straight after you delete something.
• APFS clones. A duplicated file shares its data with the original until one is changed. Tools that add up file sizes count it twice.
• Sparse files. Virtual disks, such as Docker's, can report their maximum size while using far less on disk.
• Protected folders. Without Full Disk Access, a tool cannot see into places such as Mail, Messages or Safari data, so its total comes out low.

What to look at first

If you are short on space and do not know where to begin, a handful of places account for most surprises: ~/Downloads, ~/Movies, the Photos library in ~/Pictures, ~/Library/Caches, ~/Library/Application Support, ~/Library/Containers, and on a developer's Mac ~/Library/Developer.

Check their sizes with any of the methods above before deleting anything. Knowing which one is large tells you which cleanup is worth your time.

Seeing the whole disk with Diskzy

Diskzy is a native Mac app that maps the whole disk. The first read takes a few seconds. After that it opens in about a millisecond and stays current as files change. Search finds files by name, kind, size or age.

Its System Data view breaks macOS's System Data into named parts, such as developer data, caches, app data, logs and backups, each sized and marked Safe to clear, Look first or Managed by macOS. It needs Full Disk Access to see everything, and has no analytics and no account.