It’s incredibly frustrating when you’re greeted with a “Startup disk almost full” message. Finding and freeing up disk space on your Mac can seem tricky, especially when the storage graph shows categories like “System Data” taking up swathes of space without much detail.
As a tech journalist who loves uncovering practical tips, I’ve delved into the details to help you reclaim that precious storage. Forget sketchy third-party cleaners – often, the tools you need are already built into macOS.
Here’s a comprehensive guide on how to free up disk space on your Mac, drawing on Apple’s own advice and insights from other Mac users.
Checking Your Mac’s Storage Space
Before you start deleting, it’s helpful to see what’s actually using up your space. In macOS Ventura 13 or later, you can do this by going to Apple menu > System Settings, clicking General in the sidebar, and then clicking Storage. In older macOS versions, it’s under Apple menu > About This Mac, then Storage.
The Storage window gives you a breakdown of space used by categories like Applications, Photos, Mail, Messages, and more. System Data (or Other) is a general category for files that don’t fit elsewhere, including system files, logs, caches, temporary files, app support files, and plug-ins. Note that the category sizes shown here are more of a rough idea and aren’t always precise. Free storage space is physically open space, while available storage also includes purgeable disk caches.
Finding and Deleting Large Files Manually
The most effective way to find out exactly what’s eating your space is to go straight to the source: your Mac’s hard drive.
Here’s how to use the Finder to see your file sizes:
- Open the Finder.
- From the menu bar, choose Go > Computer.
- Double-click your Mac’s boot disk, likely named “Macintosh HD”.
- From the menu bar, choose View > as List.
- Again from the menu bar, choose View > Show View Options.
- In the View Options window, check the box that says “Calculate all sizes”. Close the window.
- Wait a while. Finder will slowly calculate and display the sizes of all folders and files in the list.
- Click the “Size” column heading to sort by size, putting the largest items at the top.
Now you can start exploring. Click the disclosure triangle next to large folders to see their contents, continuing to sort by size as you go deeper. This process will show you exactly where the largest files and folders are located on your machine.
Important: This method primarily shows files within the currently logged-in user’s home folder. If you have multiple user accounts, you might need to repeat this process while logged into each account. Hidden files (like those in Library folders) can take up a lot of space. You can show invisible files in Finder by pressing Shift + Command + Period (.). Some system files are protected and cannot be deleted even with an administrator password.
Be cautious about what you delete. If you don’t recognise a large file or folder, research it online first to understand its purpose before deleting it. Deleting critical system files could cause issues.
Once you identify files you don’t need, you can select them and drag them to the Bin or select them and click Delete.
Emptying the Bin (Trash)
After you delete files by moving them to the Bin, the storage space they used isn’t actually freed up until you empty the Bin. It’s an essential step in reclaiming space. The Bin contains items you’ve deleted, although items deleted from iCloud Drive are not included in the amount of storage space shown for the Bin on your Mac.
Using macOS Storage Optimisation Recommendations
macOS offers built-in tools and recommendations to help you manage storage. You can find these in the Storage settings:
- Go to Apple menu > System Settings > General > Storage.
- Look for recommendations like “Store in iCloud”. This can move files, photos, videos, and messages to iCloud, keeping optimised versions on your Mac and downloading originals on demand. Note that storing files in iCloud uses your iCloud storage plan, which you might need to upgrade.
- Another recommendation is “Empty Bin automatically”, which will automatically erase items that have been in your Bin for over 30 days.
macOS can also automatically clear temporary files, caches, and logs that are safe to remove when space is needed.
Other Ways to Free Up Space
Beyond the main methods, there are several other areas to check:
- Downloads Folder: Delete files you no longer need from your Downloads folder. You can access it from the Dock or by choosing Go > Downloads in the Finder menu bar.
- Mail App: If you use the Mail app, clear out Junk Mail and Deleted Items. Choose Mailbox > Erase Junk Mail and Mailbox > Erase Deleted Items from the menu bar in Mail.
- Old iOS Backups: Backups of your iPhone or iPad stored on your Mac can take up significant space. You can delete old backups if you no longer need them, especially if you back up to iCloud.
- Unused Apps: Uninstall apps you no longer use. You can often do this from Launchpad or the Finder.
- Deleted User Data: If your Mac had multiple user accounts and some have been deleted, check the Users folder on Macintosh HD for any leftover data.
- Media Files: Music, films, podcasts, and other media can consume a lot of space. Delete media you can easily stream or re-download.
- Photos and Videos: Photos and videos, especially duplicates, can take up considerable space. Mac has features to help manage duplicates.
- Messages Attachments: Attachments in the Messages app can build up. There isn’t a simple setting to auto-delete old attachments while keeping messages, but you might find large attachment files using the manual Finder method mentioned earlier.
- Compressing Files: If you don’t want to delete files but need space, you can compress them to save space and expand them later when needed.
Clearing Cache Files
Cached files are temporary data stored by your system, browsers, and apps to speed up performance by making frequently accessed data quickly available. Over time, these can build up and take up space. Cache files form part of the “System Data” or “Other” storage category. Clearing your cache can free up space, remove temporary personal data, and help troubleshoot app issues.
- Browser Cache: This is generally safe and easy to clear. Each browser has its own method:
- Safari: You can manage cache and cookies via the Safari Preferences privacy tab.
- Chrome: Go to Settings > Privacy and security > Clear browsing data. Choose a time range (select “All time” to clear everything), ensure “Cached images and files” is checked, and click “Clear data”. The shortcut is Command + Shift + Delete.
- Firefox: Go to History > Clear Recent History. Select a time range (choose “Everything” for all), ensure “Cache” is checked, and click “OK”. The shortcut is Command + Shift + Delete.
- System and Application Cache: Clearing these can free up space, but you must be careful. Some cached files are important for loading things faster. Deleting files currently in use can cause problems. Unless you are an expert or troubleshooting a specific issue, it’s often best to leave system cache alone.
- To access these, open Finder, choose Go > Go to Folder.
- Type ~/Library/Caches/ for user/application caches and click Go.
- Type /Library/Caches/ for system caches and click Go (requires administrator privileges).
- You can open folders and drag unneeded files to the Bin, but err on the side of caution if you’re unsure.
Important Note: Some sources suggest using dedicated cleaning apps to safely manage system and application caches. However, other sources warn against potentially sketchy third-party utilities.
Managing iCloud Storage vs. Mac Storage
It’s important to understand that your Mac’s local storage and your iCloud storage are different. If you’re running low on iCloud storage, you can buy more or delete data stored in iCloud. To view your iCloud storage usage, go to Apple menu > System Settings, click your name (Apple Account) at the top, click iCloud, then click Manage.
Turning off an app or feature in iCloud settings might not automatically free up local space on your Mac; you might need to manually delete items if they are stored locally. The “Store in iCloud” optimisation feature is designed to help manage space by moving less-used files off your Mac when needed.
Time Machine Backups
If you use Time Machine, note that the backup disk filling up is separate from your Mac’s startup disk filling up. Time Machine automatically deletes older backups as the disk fills. You can choose to exclude items from Time Machine backups to save space on the backup disk, but this doesn’t free space on your Mac’s primary drive. Local Time Machine snapshots can temporarily use space on your startup volume. Connecting your backup drive and performing a successful backup can help manage these snapshots.
By systematically going through these methods, particularly the manual Finder approach, you can effectively find and free up disk space on your Mac without relying on questionable software. Remember to back up important data before performing large-scale deletions.
