Dupe guide

Find out what's taking up space on your Mac

macOS's built-in storage view is vague. Here's how to actually see what's eating your disk — folder by folder, file by file.

4 min read

The macOS “About This Mac > Storage” graph lumps everything into Apps, Documents, Photos, System, and a depressing grey bar called “Other.” It tells you nothing about which specific folders or files are responsible. Here’s how to actually find out.

Step 1: Get a folder-level overview

Open Terminal and run:

du -sh ~/* 2>/dev/null | sort -h

This prints every folder in your home directory, sorted by size. du -sh means “disk usage, summarized, human-readable.” Whatever’s at the bottom of the list is the biggest folder. Run it again on that folder to drill down:

du -sh ~/Documents/* 2>/dev/null | sort -h

Repeat until you find the culprit. This is the fastest way to find a 40 GB folder you forgot existed.

Step 2: Look inside Library, the hidden one

~/Library is hidden by default and frequently the place where space disappears. Show it with:

du -sh ~/Library/* 2>/dev/null | sort -h | tail -10

Common offenders here:

  1. ~/Library/Containers/com.apple.mail/ — cached email attachments
  2. ~/Library/Application Support/MobileSync/Backup/ — old iPhone backups
  3. ~/Library/Caches/ — app caches, often gigabytes
  4. ~/Library/Developer/Xcode/ — if you've ever opened Xcode, this can be 50+ GB
  5. ~/Library/Containers/com.docker.docker/ — Docker disk images

Step 3: Find individual large files

find ~ -type f -size +1G 2>/dev/null

That lists every file over 1 GB in your home folder. Drop it to +500M if nothing shows up. Old video exports, virtual machine images, and disk images are the usual suspects.

Step 4: Look at the macOS storage management view

Apple menu > About This Mac > More Info > Storage Settings. The “Documents” section here is actually useful — click it and you’ll see a list of your largest files with sizes. It also surfaces “Unsupported” file types that Apple isn’t sure how to categorize.

Step 5: The duplicate blind spot

Here’s the thing none of the above will tell you: how much of that space is duplicates. If you have a 4 GB folder, it looks identical whether it’s 4 GB of unique data or 2 GB duplicated twice. Download Dupe if you want to see the truth. It SHA-256 hashes everything and shows you exactly how many GB of duplicate data you’re storing — usually 5–30 GB on a well-used Mac.

Dupe is $14.99 once, moves dupes to the Trash (never permanent delete), and excludes system files and app bundles automatically.

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