How to free up disk space on a Mac

A nearly full startup disk makes a Mac slow, blocks macOS updates and can stop apps from saving files. The goal here is to recover real space without deleting anything you'll miss and without third-party "cleaner" apps. Everything below uses tools built into macOS and follows Apple's own guidance.

Free up space step by step

1. See what's using the space

1. Choose Apple menu > System Settings, click General in the sidebar, then Storage.
2. Wait for the coloured bar to finish calculating - it can take a minute on a full disk.
3. Note the biggest categories. Apple's list typically includes Applications, Documents, Photos, Messages, iOS Files, Trash and System Data.

2. Turn on the built-in recommendations

1. Under Recommendations on the same screen, review Store in iCloud, Optimize Storage and Empty Trash Automatically.
2. Empty Trash Automatically deletes items that have been in the Trash for 30 days - a safe one to switch on.
3. Store in iCloud moves Desktop, Documents and Photos to iCloud and keeps only recent files locally. It uses your iCloud storage plan, which may need upgrading.

3. Delete the big, safe items

1. Click (i) next to Documents and sort by size; check Large Files and Downloads first.
2. Click (i) next to iOS Files and delete old iPhone or iPad backups and software update files you no longer need.
3. Click (i) next to Messages to remove large photos, videos and attachments from old conversations.
4. Click (i) next to Applications to remove apps you don't use. Apple notes this doesn't delete documents you made with them - and it doesn't cancel subscriptions you bought in those apps.

4. Empty the Trash

1. Empty the Trash - deleted files keep using space until you do.
2. Return to Storage and confirm the available space went up.

What to delete safely (and what not to touch)

Our take: ignore cleaner apps, hunt big files instead

Disk-cleaner apps mostly delete caches that macOS rebuilds within days, and some ask for full disk access you shouldn't hand out casually. On almost every full Mac we've looked at, the space is in a handful of very large items - a forgotten 40 GB iPhone backup, a video project, a Downloads folder full of installers, or a Messages history full of videos.

So work largest-first: open Documents in Storage settings and sort by Size, then check iOS Files and Messages. Ten minutes deleting the top ten items beats an hour of clearing caches.

If it fails: System Data is huge or space won't come back

• Space didn't increase after deleting. Empty the Trash. Apple stresses that space isn't available until the Trash is emptied. Also check Recently Deleted in Photos, which keeps items for up to 30 days.
• System Data is tens of gigabytes. Much of it is temporary: caches and local Time Machine snapshots that macOS removes automatically when it needs space. Restarting the Mac lets some of it clear. Apple also suggests that starting up in safe mode clears certain system caches - useful when you need room temporarily, for example to install a macOS update. Restart normally afterwards.
• An app won't delete. Quit it first; if macOS says it's in use, restart or use safe mode and try again. Built-in apps such as Mail, Music, Notes and Maps can't be deleted.
• A third-party app left files behind. Look for an Uninstaller in the app's folder or a remove option in its settings - Apple recommends that route because it also removes login items and extensions.
• Another user account is using space. Delete accounts that are no longer needed in System Settings > Users & Groups, or ask that person to clean up their own files.

Other quick wins

• Clear your Downloads folder (Finder > Go > Downloads).
• In Mail: Mailbox > Erase Junk Mail, then Mailbox > Erase Deleted Items.
• Delete old iPhone or iPad backups (iOS Files category).
• Uninstall apps you no longer use (Applications category).
• Delete media you can stream or download again.
• Remove user accounts that no longer need access to the Mac.
• Compress files you want to keep but rarely open.

Move instead of delete

If you want to keep large files but not on the internal drive:

1. Connect an external SSD formatted as APFS or Mac OS Extended.
2. For photos, quit Photos, drag the Photos Library from your Pictures folder to the external drive, then open it from there while holding Option and choosing Other Library.
3. For finished projects, drag the folder to the drive, check it opens, then delete the original.
4. Keep a second copy somewhere else - an external drive on its own isn't a backup.

Compressing rarely-used folders (right-click > Compress) also helps for documents, though not for photos and videos, which are already compressed.

How much free space should you keep?

There's no official percentage, but macOS needs working room for virtual memory, caches and updates. As a practical rule, keep at least 10-15% of the drive free and more before a major macOS upgrade, which needs extra temporary space to download and install. If you're constantly at the limit, iCloud's Optimize options or an external drive are cheaper than fighting it every month. Slow browsing on a full Mac is often helped by clearing Chrome's cache as well.