Mac Storage Full? Here's Where the Space Actually Went

"Your disk is almost full" is a special kind of stress, usually arriving right when you need to install an update or export a video. The good news: on most Macs the space is hiding in a handful of predictable places. Here's where to look, biggest wins first.

Start with the built-in storage tool

Open System Settings → General → Storage. Give it a minute to calculate. You'll see a coloured bar showing what's using space, and below it a list of categories with recommendations.

Click the ⓘ button next to each category to see the biggest items inside. This screen alone often finds 20 GB or more.

1. Your Downloads folder

It's usually the worst offender: installers you ran once, ZIP files you already unzipped, videos you downloaded "for later" in 2023.

Open Downloads in Finder, switch to List view and sort by Size. Delete anything you don't need. Installers (.dmg and .pkg files) can go once the app is installed.

2. Old iPhone and iPad backups

If you ever backed up an iPhone to your Mac, those backups can be tens of gigabytes each, and old ones stick around forever.

Connect any device (or just open Finder), select your iPhone in the sidebar, and click Manage Backups. Delete backups of devices you no longer own. If your phone backs up to iCloud, you may not need the local ones at all.

3. Big files you forgot about

In Finder, press Cmd + F, change "Kind" to Other, pick File Size, and set it to is greater than 1 GB. You'll quickly find old video exports, virtual machine images and disk images.

4. Photos and Music

• Photos: if you use iCloud Photos, turn on Optimize Mac Storage in Photos settings. Full-resolution originals stay in iCloud, and your Mac keeps smaller versions.
• Music and TV: downloaded songs, movies and podcasts add up. Remove downloads you've already watched or don't listen to anymore.

5. Empty the Trash (seriously)

Deleted files sit in the Trash, still using space, until you empty it. In the Storage settings you can turn on Empty Trash Automatically, which removes items after 30 days.

6. For developers: the hidden giants

If you write code, check these:

• Xcode keeps simulators, device support files and build data that can grow huge. Remove simulators you don't use, and clear old build data from Xcode settings.
• Docker images and volumes. Clean up unused ones from Docker Desktop.
• node_modules folders in old projects. Each one can be hundreds of megabytes. Delete them in projects you're not working on; you can reinstall later.
• Local AI models. If you've tried running AI on your laptop, those model files are several gigabytes each. See how to run an AI model on your laptop for how to list and remove them.

What about "System Data"?

That mysterious grey section includes caches, logs, temporary files and Time Machine snapshots. macOS manages most of it automatically and clears space when you need it. Restarting your Mac often shrinks it. Avoid "Mac cleaner" apps that promise to clear it for you. They rarely help much and some are pushy about paid upgrades.

Keep it from filling up again

• Turn on Empty Trash Automatically and Optimize Mac Storage.
• Clear your Downloads folder once a month.
• Keep big archives (old video projects, raw photos) on an external drive. Bonus: that's step one of a good backup plan. See the 3-2-1 backup rule.