Reduce Storage on Your Mac

My Mac’s storage was nearly full — 204GB of “System Data” was eating up space. After some investigation, I managed to free up about 70GB. Here’s what I did and what I learned along the way.

What Is “System Data”?

In macOS, System Data (previously called “Other”) includes caches, logs, Time Machine local snapshots, app leftovers, and temporary files. You can’t eliminate it entirely since the OS needs some of it to function, but you can definitely trim it down.

Step 1: Find Out What’s Taking Up Space

Before cleaning anything, check where the storage is actually being used. Open Terminal and run:

sudo du -x -d 5 -h /System/Volumes/Data 2>/dev/null | sort -hr | head -20

This gives you a top-20 list of the largest directories. In my case, the output looked like this:

204G  /System/Volumes/Data
 80G  /System/Volumes/Data/private/var
 76G  /System/Volumes/Data/private/var/folders
 71G  /System/Volumes/Data/private/var/folders/zz/zyxvpxvq...
 67G  /System/Volumes/Data/Users/username
 41G  /System/Volumes/Data/Users/username/Library
 16G  /System/Volumes/Data/System/Library
 15G  /System/Volumes/Data/Applications
 ...

The biggest culprit was private/var/folders — 76GB of cached temporary files.

Step 2: Boot into Safe Mode (Most Effective)

This is Apple’s built-in way to safely clean up system caches. When you start your Mac in Safe Mode, macOS automatically scans and removes unnecessary temporary files from private/var/folders.

How to enter Safe Mode

Apple Silicon

1. Shut down your Mac completely.
2. Press and hold the power button until “Loading startup options” appears.
3. Select your startup disk.
4. Hold Shift and click “Continue in Safe Mode”.
5. After it boots, log in and then restart normally.

Intel

1. Shut down your Mac completely.
2. Turn it on by pressing and holding the Shift key until you see the login window.
3. Log in (you may need to log in twice).
4. Restart normally.

That’s it. In my case, this single step reduced my total from 204GB to 135GB — roughly 70GB freed.

⚠️ Do NOT manually delete files inside private/var/folders

The OS reads and writes to these directories in real time. Deleting them can cause kernel panics or make your Mac unable to boot.

Other Tips

Delete Old Time Machine Snapshots

Many articles suggest that Time Machine local snapshots are a major cause of bloated storage, but in my case they weren’t the issue — and I suspect the same is true for most people.

If Time Machine creates local snapshots, list and remove them with:

tmutil listlocalsnapshots /
sudo tmutil deletelocalsnapshots /

Remove Old iOS Device Backups

Go to System Settings > General > Storage > iOS Devices and delete any backups you no longer need.

Summary

The biggest win was simply booting into Safe Mode. If your Mac feels sluggish or you’re running low on storage, try that first — it takes just a few minutes and can make a huge difference.