Dupe guide

Mac running out of space — the 8 things to check first

When your Mac is almost full, these eight spots account for nearly all the recoverable space. Check them in order.

4 min read

Your Mac is bleating about low disk space and you’ve got no idea where the gigabytes went. Before you start uninstalling apps at random or buying a bigger external drive, there’s a short list of places that account for almost all of the slack on a typical machine.

The 8 places to look, in order

Work top to bottom. Each step takes a couple of minutes and most people find what they need before reaching the bottom.

  1. Downloads. Open Finder, go to Downloads, sort by size. Installer DMGs, ZIPs, and old video files are usually the worst offenders. Most of this is safe to delete outright.
  2. Trash. Sounds obvious. People forget. Right-click the Trash icon in the Dock and check the size before you empty it — a year of dragged files can be 20+ GB.
  3. iOS and iPad backups. Open Finder, click your iPhone, then "Manage Backups." Old device backups eat 5–80 GB and nobody ever thinks to look there.
  4. Photos library. If you have iCloud Photos with "Download Originals" turned on, the local copy can balloon. Switch to "Optimize Mac Storage" in Photos > Settings > iCloud.
  5. Mail downloads. Mail caches every attachment you ever opened in ~/Library/Containers/com.apple.mail/Data/Library/Mail Downloads/. Often several GB.
  6. Old apps and their leftovers. Uninstalling an app via drag-to-Trash leaves caches and preferences behind in ~/Library. Cleaning these up gets you back hundreds of MB per app.
  7. Large files anywhere. Run find ~ -type f -size +1G 2>/dev/null in Terminal to list every file over 1 GB in your home folder. Old video projects, virtual machines, and Docker images live here.
  8. Duplicates. The sneaky one. The same photo imported from two devices, the same PDF saved to Desktop and Downloads, the same project folder copied "just in case." On most Macs duplicates account for 5–30 GB.

Quick command to size up your home folder

Open Terminal and run:

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

That gives you a sorted list of every top-level folder in your home directory by size. Whatever’s at the bottom is where to look next.

The duplicate angle

If you’ve worked through 1–7 and still need more space, duplicates are almost certainly the answer — they’re invisible to Finder’s “size” view because each copy looks legitimate on its own. Download Dupe to scan for byte-identical duplicates (SHA-256 hashed, so it won’t false-positive on same-sized files). It moves duplicates to the Trash so you can restore anything you change your mind on, and it never touches system files or app bundles.

It’s a $14.99 one-time purchase — about the cost of two months of an iCloud upgrade.

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