How to Free Up Space on Your Mac: The Complete Guide

The first time you see your Mac say “Your disk is almost full,” you probably blame Photos or Downloads. Then you check, and Photos is 12GB. Downloads is 4GB. So where did the other 200GB go? It’s almost always in three places nobody thinks to check: System Data, app caches that never got cleared, and old iOS backups from a phone you don’t even own anymore.

This guide walks through every meaningful spot where macOS hides storage, in roughly the order that pays off best. You won’t need any sketchy tools. You will need about 20 minutes if you do it manually — or about two minutes if you let something else do the hunting for you.

Start with the built-in storage view

Before deleting anything, see what you’re actually working with. Apple menu → System Settings → General → Storage. Wait a few seconds for the colored bar at the top to fill in.

That bar lies a little. Specifically, the “System Data” segment lumps together caches, logs, plugin data, snapshots, language packs, and stuff macOS genuinely needs. Some of it is reclaimable. Some isn’t. We’ll get to that.

Below the bar you’ll see a list — Applications, Documents, iCloud Drive, Mail, Photos, Trash. Each row has a small “i” button. Click it. Sonoma 14 and Sequoia 15 both let you sort the contents by size and delete from there. This is the single most useful built-in feature for a quick win.

The first sweep: easy wins

Hit these in order. Most people reclaim 10–30GB in the first ten minutes.

1. Empty the Trash. Right-click the Trash icon → Empty. Files in there still count against your storage.
2. Clear the Downloads folder. ~/Downloads. Open Finder, sort by Size, and start at the top. DMG installers, ZIP archives, screenshots — most of it can go.
3. Delete old iOS backups. Finder → your iPhone in the sidebar → Manage Backups. A single iPhone backup can be 50GB+. Pure dead weight.
4. Uninstall apps you haven’t opened in six months. Launchpad → press and hold an app icon → click the X (for App Store apps), or drag from /Applications to Trash for the rest. Don’t stop there — see the next section about leftovers.
5. Delete videos in Messages. Messages can hoard hundreds of MP4 attachments without you realizing.

Skip the manual huntSweep finds every cache, log, and forgotten file in seconds — and only removes what you OK. Download Sweep free →

Why dragging an app to the Trash isn’t enough

When you drag, say, Slack to the Trash, you’re deleting maybe 400MB of binary. The 1.2GB of cached messages, app support files, and preferences in ~/Library/Application Support/Slack and ~/Library/Caches/com.tinyspeck.slackmacgap stays exactly where it is. Forever.

Multiply that across every app you’ve ever installed and never fully cleaned up, and you’ve found a chunk of your “missing” space. To do this manually:

• Open Finder, hit Cmd+Shift+G, type ~/Library
• Check Application Support, Caches, Containers, Preferences, Logs, and Saved Application State
• Look for folders or .plist files referencing the app you uninstalled

It’s tedious. Honestly, it’s the kind of thing nobody does until they have to. Sweep’s app uninstaller does this whole hunt automatically when you remove an app — every leftover, queued up for one approval before deletion. If you’re going to do it manually, just budget the time.

Tackling the System Data monster

System Data is where most people lose 50–150GB without ever knowing why. Here’s what’s in there that you can actually clean:

• User caches at ~/Library/Caches — Spotify alone often holds 4–8GB here
• System logs at /var/log and ~/Library/Logs
• iOS device support files — old simulator runtimes, device support files
• Time Machine local snapshots (more on these in a minute)
• Mail downloads — every attachment you’ve ever previewed
• Old Xcode derived data if you’ve ever opened Xcode — easily 20–40GB
• Language files for apps that ship with 30+ localizations you don’t use

What you should NOT touch in System Data: anything in /System, kernel extensions, framework files, macOS recovery snapshots after an OS update.

Time Machine is probably eating your disk

Even if your backup drive is unplugged, macOS keeps “local snapshots” of your data on the internal drive — APFS snapshots that act as a safety net between backups. Useful in theory. Terrible for storage in practice.

To check what’s there, open Terminal and run:

tmutil listlocalsnapshots /

If you see a bunch of dated entries, that’s gigabytes you can’t see in Finder. To delete a single snapshot:

tmutil deletelocalsnapshots <date>

Or open Disk Utility, select your Macintosh HD volume, View → Show APFS Snapshots, and delete from there. macOS does eventually clean these up on its own when storage runs low, but if you’re staring at a “Disk Almost Full” warning right now, you don’t have time to wait for that.

Photos and iCloud: the silent storage sink

Photos library size depends entirely on whether you have “Optimize Mac Storage” turned on. Check Photos → Settings → iCloud. With Optimize on, your Mac keeps thumbnails locally and pulls full resolution on demand. With “Download Originals” on, you’ve got the full library — which on a heavy iPhone user can be 200GB+.

A few real options:

• Toggle to Optimize and let macOS download originals only when you actually open a photo
• Move your Photos Library to an external drive (Photos → Quit, drag the .photoslibrary file to your external, then Option-launch Photos and pick the new location)
• Use the Duplicates album in Photos (built-in since Ventura) to merge obvious dupes

iCloud Drive has the same problem. Files in ~/Library/Mobile Documents/com~apple~CloudDocs/ may be either local or just stubs. Right-click any folder → “Remove Download” pushes its contents back to the cloud while keeping the placeholder.

The deep clean: caches you can actually delete

These are the folders you can safely empty without breaking anything:

• ~/Library/Caches/ — app-level caches. Worst case, an app rebuilds them on next launch.
• ~/Library/Logs/ — diagnostic logs. Useful only if you’re actively debugging an issue.
• /Library/Caches/ — system-wide caches (admin password required)
• ~/Library/Containers/<app>/Data/Library/Caches/ — sandboxed app caches

What you should NOT empty:

• ~/Library/Application Support (this is real app data — settings, projects, etc.)
• ~/Library/Containers (the parent folder — the cache subfolder inside is fine)
• ~/Library/Mobile Documents (your iCloud Drive)

A common mistake is cleaning these while the app is open. Quit the app first.

Reclaim 20+ gigs in one passSweep finds the caches, snapshots, and old downloads adding up to most of your “System Data.” Free download →

The Mail trap

Mail keeps a copy of every attachment you’ve ever previewed, in ~/Library/Mail/V10/MailData/. On accounts you’ve had for years, this folder can be 20GB by itself. The fix is to rebuild your mailbox: Mailbox menu → Rebuild. It’s slow — give it the rest of an hour — but it cleans out orphaned attachments and re-syncs from the server.

If you don’t want to wait, just delete old emails with attachments. Sort by Size in any mailbox (View → Sort By → Size) and start with the big ones.

What to do when nothing else works

If you’ve cleaned everything obvious and still have a near-full disk, you’ve got one of three problems:

1. A runaway log file from a misbehaving app — check /var/log/ and /Library/Logs/DiagnosticReports/ for anything multi-gig
2. Time Machine snapshots that aren’t auto-clearing — try sudo tmutil thinlocalsnapshots / 9999999999 4
3. A virtual machine or container disk image you forgot about — search Spotlight for .vmdk, .qcow2, .dmg larger than 5GB

After all that, restart your Mac. Some space won’t actually free up until macOS clears its working files on reboot — that’s normal, not a glitch.

The honest truth about Mac storage: it’s not one big monster eating your disk. It’s a hundred small ones. Cleaning manually works, but it takes patience and it’s the kind of thing you’ll have to do again in three months. Tools like Sweep exist because the hunt is repetitive — same folders, same junk, every time. Whether you do it by hand or click a button is up to you. Just don’t ignore the warning until your Mac stops saving documents.