LighterMac

Why does my Mac storage keep filling up?

The short answer

Most of what fills a Mac is designed to grow back. Caches refill as you use your apps, chat apps download attachments again, iCloud downloads files you open, and developer tools rebuild their folders. A one-time cleanup works for a few weeks. Then you're back where you started.

What refills fastest

  • Browser and app caches. They start growing again the next time you open the app.
  • Chat app files. Every image in a busy Slack or WhatsApp group is saved on your Mac.
  • iCloud Drive and Photos. Every file you open is downloaded and kept, unless Optimize Mac Storage is on.
  • Developer folders. Xcode, Gradle, npm and Docker can add gigabytes a week.

Slow it down, without any app

  1. In System Settings → General → Storage, turn on Empty Trash Automatically.
  2. Turn on Optimize Mac Storage for iCloud Drive and for Photos. How →
  3. Write down your free space once a week. If it drops by more than 5 GB, something is growing fast.