How to Clean Up a Mac and Free Up GBs of Storage (Free Methods)

Most "clean up Mac" guides skip the boring obvious stuff and try to nudge you into a $60/year subscription. I'd rather be honest: you can usually get 20–50GB back in an afternoon using a handful of built-in tools and one free app. That's the checklist below, roughly in order of return on effort.

Quick reality check: where your storage actually goes

On a typical MacBook after 12–18 months of use:

• Documents — 10–30% (often old downloads + forgotten projects).
• Apps — 20–40 GB for heavy users (Xcode alone is 10+ GB).
• System Data — the mystery category. Caches, logs, swap, Xcode derived data, old iOS backups. Frequently 20–80 GB.
• Messages / Mail / Photos — attachments balloon quietly.
• Trash — yes, people forget to empty it.

"System Data" is where cleanup pays the biggest dividends, because macOS's built-in Storage tool doesn't fully show what's in it. That's the category a Mac cleaner actually helps with.

Step 1 — Start with macOS Storage management (free, built-in)

Apple menu → System Settings → General → Storage.

You'll see a color bar and a list of categories. Click each to expand. The recommendations at the top are the low-hanging fruit:

• Store in iCloud — moves Desktop/Documents to iCloud, keeping recent files local.
• Optimize Storage — removes watched Apple TV content.
• Empty Trash Automatically — deletes Trash items older than 30 days.
• Reduce Clutter — opens a file browser for large/old files.

The "Reduce Clutter" view is the most useful — sort by size, scan the top 50, delete what you don't recognize.

Step 2 — Empty the Trash (yes, really)

Finder → Empty Trash. And while you're at it, check the Trash on each external drive — those each have their own, and people forget. Photos also has a "Recently Deleted" album that hangs onto stuff for 30 days. Clearing that out occasionally surprises me with a gigabyte or two.

Step 3 — Delete the Downloads folder's forgotten layer

Finder → Downloads → sort by Date Added (oldest first) or by Size (largest first).

What you'll typically find:

• Old .dmg installers you already installed the app from.
• Zip files from projects that shipped two jobs ago.
• 20 copies of the same PDF.

This is usually worth 5–15 GB by itself.

Step 4 — Delete apps you don't use

Finder → Applications. Sort by Size. Look at the bottom of the list (where the big ones are).

Common surprises:

• Xcode — 10–15 GB base, plus another 10–30 GB of derived data.
• Adobe Creative Cloud apps — 5+ GB each.
• Microsoft Office suite — 5 GB for Word + Excel + PowerPoint.
• Unity / Unreal Engine — tens of GB if you tried game dev once.
• Old demos of tools you evaluated and forgot.

Drag to Trash, or use a Mac cleaner's uninstaller (which also removes preferences, caches, and login items the app created). Drag-to-trash leaves those behind — usually a few hundred MB per app.

Step 5 — Clean out Xcode (if you're a developer)

Xcode's derived data and simulators are often the single biggest space hog on a developer's Mac.

rm -rf ~/Library/Developer/Xcode/DerivedData/*
xcrun simctl delete unavailable

The first line clears build caches (Xcode regenerates them as needed). The second removes simulators for iOS/iPadOS versions you no longer target. Combined, often 10–50 GB back.

Step 6 — Delete old iOS backups

If you've ever backed up an iPhone to your Mac, those backups might still be sitting there. Each one is 10–100 GB depending on the device.

Finder → your iPhone in the sidebar → Manage Backups → delete old ones. Or manually:

~/Library/Application Support/MobileSync/Backup/

Step 7 — Clear system caches and logs

We covered this in detail in our Mac cache cleaner guide. Short version:

rm -rf ~/Library/Caches/*
sudo rm -rf /Library/Caches/*

Or use a free tool like MacFreeup's Smart Scan to do it with previews. Typically 2–10 GB on a normal Mac.

Step 8 — Clean Mail and Messages attachments

These sneak up on people.

• Mail: Mailbox → Erase Junk Mail and Erase Deleted Items. For attachments: Finder → Cmd + Shift + G → ~/Library/Mail/ → check sizes of the mailbox folders.
• Messages: open Messages → Settings → General → uncheck "Save history when conversations are closed". Then manually delete old conversations with large media.

Step 9 — Clear browser data

Chrome's profile folder gets huge. Cmd + Shift + Delete inside Chrome → All time → check "Cached images and files" → Clear.

Safari: Develop menu → Empty Caches (enable the Develop menu in Settings → Advanced first).

Step 10 — Run a free Mac cleaner for the leftover System Data

By this point you've cleared the obvious categories. What remains is the System Data blob macOS's built-in tool can't show you in detail: app leftovers, old TimeMachine local snapshots, crash reports, orphaned preference files, etc.

A free Mac cleaner like MacFreeup (or OnyX, for the more manual approach) finds these and lets you preview before deleting. Usually another 3–10 GB.

Step 11 — Consider offloading

If you still can't find space:

• Move Photos library to an external SSD (File → Export → External Drive, then relink).
• Move old Time Machine backups off your primary disk.
• Enable iCloud Drive "Optimize Mac Storage."
• Archive old Xcode projects to external or cloud.

What a Mac cleaner is actually good for

You'll notice most of the steps above don't require any third-party app. That's honest: macOS plus Finder plus Terminal covers 80% of cleanup. A free Mac cleaner earns its spot for three specific things:

1. Finding what macOS's Storage tool hides — the System Data category's actual contents.
2. Removing app leftovers fully — preferences, helper agents, launch daemons that survive drag-to-trash uninstalls.
3. Doing it all in one pass with previews — instead of opening Finder at 10 different paths.

FAQ

How do I free up GBs on my Mac without buying anything?

Empty Trash, delete the Downloads folder, uninstall unused apps, clear browser caches, and run rm -rf ~/Library/Caches/*. Most people get 10–30 GB back from this alone, no app required.

What's the best free app to free up space on a Mac?

MacFreeup's free tier handles caches, logs, leftovers, and large files. OnyX is fully free for maintenance tasks. Either is fine; pick the UI you prefer.

How do I clean up my Mac when it's full?

In order: empty Trash → Downloads folder → Storage management recommendations → uninstall largest apps → clear caches → run a free cleaner. If still full, offload Photos or video libraries to external storage.

What takes up System Data on my Mac?

Caches, logs, Xcode derived data, old iOS backups, Time Machine local snapshots, Mail attachments, Messages media, and app leftovers. macOS groups all of these under one label, which is why it looks mysterious.

If you only do one thing

You really don't need a $60/year subscription to clean up a Mac. Built-in tools plus one free cleaner gets you there. Run through steps 1–7 once a quarter — put it on the calendar if you have to — and you'll probably never see the "Your disk is almost full" banner again. Future you will be grateful.