What Causes the Disk Full Message
The most common cause of the disk full message on a Mac is simply a lack of available storage space on the startup drive. As files accumulate over time from applications, photos, videos, music, and more, the storage capacity gets used up. Macs generally start warning about low disk space when storage drops below 10-20GB of free space.
Large individual files like videos, system backups, or virtual machine files can also quickly eat up disk space. For example, storing many RAW photo files from a DSLR camera or downloading a huge game on Steam can push storage over the limit.
System files and caches can also gradually accumulate and take up significant space. Caches help apps and web browsers run more efficiently by storing temporary data, but this cached data can build up over time. The macOS system itself also uses storage for core files, logs, caches, and more.
Check Available Storage
The first step in diagnosing the disk full message on a Mac is to check your available storage. To do this:
1. Open About This Mac by going to the Apple menu and selecting “About This Mac.”1
2. In the About This Mac window, click on the “Storage” tab to view storage stats for your different disks and volumes.
3. Look to see which disk or volume is full or nearly full. This is likely your boot drive, often named “Macintosh HD.” Note the available space compared to capacity.
If you see only a small amount of space left, such as less than 10GB on a 256GB disk, the disk is indeed nearly full.
Checking About This Mac provides a quick overview of storage space to identify which disk needs troubleshooting.2 If one disk is full, you can focus efforts on freeing space there.
Locate Large Files
One of the best ways to free up storage space on your Mac is to find and remove large, unnecessary files. The Finder app on Mac makes it easy to sort files by size and identify candidates to delete or move.
To locate your largest files using Finder:
- Open a Finder window and navigate to the location you want to search, like your Documents folder or main hard drive.
- Click View > Arrange By > Size. This will sort all files from largest to smallest.
- Scroll through the list and look for files that can be removed, like old backups, downloads you no longer need, or unused media files. Movies and RAW photo files often consume a lot of unused space.
- To see large files across your whole system, choose About This Mac from the Apple menu then click Storage > Manage to open Disk Utility. Here you can see all files ordered by size.
Be careful not to delete anything you may still need. Focus on files you can confidently remove like hidden system caches, downloads, or duplicates. Refer to your recent activity to identify good candidates. Moving files to an external drive can also quickly free up precious space.
According to Setapp, using a dedicated utility like CleanMyMac X or HoudahSpot makes finding and deleting large files even easier. But the native macOS tools provide a simple starting point.
Clear Caches
One way to free up disk space is by clearing unnecessary caches on your Mac. Browser caches in particular can build up over time and take up significant storage space. To clear browser caches:
Open the Finder and go to the following folder: ~/Library/Caches. This is where your browser cache files are stored. Open the folders for each browser you use (Chrome, Safari, Firefox etc.) and delete the files inside to clear the cache. For example, delete all files inside the Chrome folder to clear the Chrome cache.
You can also clear the system caches and other temporary files that build up. Open the Downloads folder in Finder and empty it out by moving files to another location or deleting them. Other folders like /Library/Caches can also be cleared out, but exercise caution and avoid deleting files you don’t recognize.
Clearing the browser caches and Downloads folder is a safe way to free up a lot of storage space on a full disk. Just be sure not to delete any current downloads or other files you still need.
Delete Unneeded Files
One of the easiest ways to free up storage space on your Mac is by deleting old and unneeded files that you no longer use. Here are some tips for identifying and removing unused files:
Go through your Documents folder and delete any old documents, photos, videos or other files you no longer need. You can sort by date modified to easily find older files. It’s safe to remove documents and other files you haven’t opened in over a year.
Check for unused apps in your Applications folder and delete any you haven’t used recently and don’t need anymore. You can sort by date added to easily find apps you haven’t opened in a long time. Be sure not to delete any essential system apps.
Empty the Trash to permanently remove any files you’ve deleted. You can do this by right-clicking the Trash icon in the Dock and selecting Empty Trash. This will free up the disk space being used by the deleted files. Remember that emptying the Trash permanently removes files, so be sure you have backups of anything important.
Regularly removing old and unnecessary files is an easy way to free up gigabytes of storage space on your Mac’s hard drive. Focus on documents, media files and apps you no longer need to reclaim the most space.
Move Files to External Storage
One way to free up storage space on your Mac is to move files to external storage devices like an external hard drive or cloud storage. This can help remove large files like photos, videos, music, and documents from the internal drive to clear space.
An external hard drive provides a physical storage device that you can connect to your Mac via USB, Thunderbolt, or FireWire. Once connected, you can transfer files by dragging and dropping them from your Mac to the external drive in Finder. Popular hard drives like the Seagate Portable or WD My Passport are plug-and-play devices that work with Mac right out of the box.
Cloud storage services like iCloud, Dropbox, Google Drive, and OneDrive also allow you to store files online instead of on your internal drive. Sign up for a cloud storage account, install the desktop app, then move files into your cloud account’s folder on your Mac. The files will be uploaded and removed from the local drive, but still accessible through the cloud service. Cloud storage is best for important files you want accessible anywhere.
According to Apple Support, external storage lets you physically move large files off your Mac to make space on the internal drive. Cloud services also provide storage but keep files accessible through the internet.
Upgrade Internal Storage
One way to resolve the disk full error on a Mac is to upgrade the internal hard drive or solid state drive (SSD) with a higher capacity drive. Most MacBook Pro, MacBook Air, and iMac models allow you to replace the internal drive, though the process varies by model. Upgrading to a larger drive like a 1TB or 2TB SSD can provide ample storage space.
Before upgrading, be sure to back up your data to an external drive. Then you can replace the internal HDD or SSD with a new higher capacity drive. You’ll need to purchase a compatible drive for your specific Mac model and have the proper tools to open up your Mac and swap the drive. Refer to this guide for steps on upgrading a MacBook Pro drive.
After installing the new drive, you’ll need to reinstall macOS and restore your data from backup. Be sure to properly format the new drive first. Upgrading to a roomier internal drive can be a more convenient and cost-effective way to fix disk full errors compared to relying solely on external drives.
Use Disk Management Tools
Two useful disk management tools on Mac are Disk Utility and third-party cleaners like DaisyDisk. Disk Utility is included for free with every Mac and can analyze storage usage to help identify large files or trouble spots. To use it, go to Applications > Utilities > Disk Utility and click the storage device you want to analyze. In the toolbar, click “First Aid” to check for errors and then click “Manage” to analyze usage. This breakdown can show what types of files are taking up space.
Third-party cleaners like DaisyDisk provide more detailed visualizations for spotting and deleting large unused files. DaisyDisk scans storage and generates an interactive map of disk usage with color coded blocks representing file size. You can click blocks to drill down and see specific folders and files. Tools are included for previewing, deleting, moving, or compressing files to free up space. Many users find visual disk cleaners like DaisyDisk helpful for quickly finding and clearing disk hogs.
Adjust System Preferences
One way to free up storage space on your Mac is to adjust your System Preferences settings. Two specific settings to focus on are Time Machine backups and optimized storage:
Turn off local Time Machine backups
Time Machine enables you to back up your entire Mac and restore files if needed. By default, it saves hourly backups locally before transferring them to your designated external backup drive. Having these local backups stored can quickly eat up storage space. You can disable local backups by going to System Preferences > Time Machine and unchecking “Back Up Automatically.” Just make sure you have an external drive configured properly to save your backups.
Set optimized storage settings
Starting in macOS Sierra, Apple introduced optimized storage, which helps manage your disk space. Enable this by going to System Preferences > Apple ID > iCloud and checking the “Optimize Mac Storage” box. This will automatically offload infrequently used files to iCloud and delete items that have been in your trash for over 30 days. You can also have your Mac automatically remove watched iTunes movies and TV shows. This can help reduce the amount of disk space used locally.
Citing Sources:
https://support.apple.com/en-us/HT206996
https://macpaw.com/how-to/free-up-space-mac
When to Seek Professional Help
If you’ve tried the software troubleshooting tools like Disk Utility and clearing caches to free up space, but are still getting the disk full error, it may be time to seek professional help. The Apple Geniuses at the Apple Store are trained specifically to troubleshoot Mac issues like a full disk. Make an appointment and bring your Mac into your local Apple Store. The Geniuses can run diagnostics to pinpoint any underlying issues causing the disk to fill up, and suggest next steps like upgrading your storage.[1]
If your Mac’s internal storage is constantly filling up and you need more capacity, seeking professional help for a storage upgrade is recommended. The Geniuses can help you determine the best storage solution for your needs and budget, like a higher capacity internal SSD or Fusion Drive. They can also physically install the new hardware safely and correctly. Upgrading internal storage yourself is not recommended unless you have technical expertise with Mac repairs.[2]
Bringing your Mac to a professional can save you time and ensure any storage upgrades are done properly. Their expertise can also identify any other factors contributing to a constantly full disk.