How to fix the “Startup Disk Full” error on your Mac

As of 2022, Mac hard drives are as spacious as ever. The maximum hard drive size you can currently get is 8 TB, but sorry, that’s a Mac Pro or a top MacBook Pro. Another issue is the macOS itself. The modern macOS versions like macOS Monterey, which is now succeeded by macOS Ventura, are increasingly browser-oriented and aim to perform most of the work online. It for sure reduces the toll on your hard drive. But where is our disk leaking then?

One answer is hidden website cache. Artem Russakovskii from Android Police spotted that Chrome creates notoriously large cache folders even after you’ve visited seemingly simple sites like In some cases, it was 9GB worth of cache collected from one site alone. So, these days, it’s essential to know how to clean the startup disk on Mac. Because there comes a day in the life of every Mac user when the message “Your startup disk is almost full” will hit you hard. But how could a full startup disk affect you?

Let’s start with the beginning: what is a startup disk? Well, it’s the hard drive that contains your operating system, which makes it the most important disk of all. So, when the “Your startup disk is almost full” message pops up, it basically means you are running out of space on your primary disk drive, and that is very bad news.

What does it mean when your Mac says the disk is full?
"Your disk is full" message

When a Mac startup disk is reaching full capacity, it is bad news for two reasons:

  1. Soon you’ll run out of space entirely.

  2. A disk that is full (or even near full) is going to perform slowly.

What most people don’t realize is that their Mac actually converts the available space on their startup disk into virtual memory, which you use for day-to-day operations. Ideally, 10% of the disk should be free to leave your Mac’s OS enough space to operate. Therefore, if you’re running low on space, you’re heading for big problems.

How to check disk space on Mac

To get to the root of the problem and find the solution, you must discover what is taking up all the space on your startup disk drive.

To have an overview of how your space is being used, simply follow these steps:

From here, you’ll be able to see exactly how much space you’ve got left and what’s eating up the used one. If you are running out of available disk space, it's time to delete some files or install a new hard drive.

Luckily, your disk will be full of movies, photos, and audio. Why luckily? Because these files are easy to remove or move to another location. Any external drive or cloud storage will do the trick, and your Mac’s going to thank you for leaving it space to breathe.

However, there’s another scenario in which other data is taking up the free space, with files you cannot or do not want to delete. This situation’s a bit trickier, but don’t worry. These tips will surely give your Mac some extra space. We’ve grouped them into two main categories:

So, let’s start fixing your Mac right now.

10 Essential tips to clear the startup disk on a Mac

Believe it or not, one of your Mac’s occupations is to create junk. But don’t blame it; it’s just doing its job. The Mac’s system, like all the other operating systems, depends on creating temporary files, caches, and backups to perform correctly. However, after this data has done its part, it remains latent on your Mac, killing space for no purpose.

The good news is that it’s extremely simple to remove these useless files, freeing up gigabytes and fixing your startup disk full problem without affecting your personal data.

So here is how you can fix the “Your startup disk is almost full” error message by deleting the files you don’t need and never use.

tip 1

Delete App Cache (System Junk)

The funny thing with cache files is that they are as necessary as they are useless. At first, caches serve a major purpose, as they get created in order to speed up processes. But once that process ends, you’re left with temporary junk generated by apps and system processes. Unless you remove them yourself, they will remain on your Mac for long. If you don’t, then these temporary files will become a permanent problem for your hard drive, as they will continue to pile up and make your startup disk full.

Fortunately, it’s an easy problem to solve simply by removing them. And don’t worry, your apps will soon refresh their caches and be back up to speed in no time.

To remove app cache files and clean up a startup disk, follow these steps:

Note that there is always a small risk when manually deleting files — you might pick the wrong folder, so consider backing up these folders before you start deleting them.

Alternatively, you can clean up all caches in a fraction of the time and with 100% confidence if you download CleanMyMac X. This is how easy it is to delete tons of system junk at the same time using this flow:

CleanMyMac X - System junk scan complete

Download Free Version

tip 2

Take out the Trash

Sometimes, we overlook the most obvious solutions because we think the fix must necessarily involve some complex operation. But when there's not enough disk space, Mac can be saved through the simplest trick. 

The fact is that your Trash is a graveyard for files you no longer need. Still, these files keep taking up space on your Mac’s drive. So, you’ve probably guessed it: take out the Trash and press “empty” to completely get rid of those piles of useless data.Empty Trash

We’re also going to satisfy your need for secret solutions by pointing out something you might not have thought about: every single app has its own trash folder that also stores useless gigabytes. The Mail app is one example, but there are many more. Just like the general Trash, you need to empty these folders in order actually to remove the junk and clear up disk space.

Once you empty all the trash folders in all the apps, you’ll be ready to move to the next tip. Ready? Let’s go.

tip 3

Remove Time Machine Backups

We love Time Machine because it creates important backups. But when your Mac can’t function due to a lack of disk space, there has to be a sacrifice. You can start with removing past Time Machine “snapshots” stored locally on your Mac. So, the first step towards removing the “startup disk full” message is to take care of these backups. Yes, by taking care, we mean removing them. To do it, all you need is to temporarily turn off your Time Machine.

Then, you should give it a few minutes to take effect. Your local Time Machine snapshots will be deleted.

tip 4

Delete Browser Cache

Your internet browser creates caches every time you visit a new page to load it faster on your next visit. However, doing this literally for every page keeps your browser folder cluttered, creating an even bigger problem.

So, if you’re wondering how to safely clean a startup disk on Mac, removing browser junk is definitely a priority.

Every browser has a different cache removal process, so to remove unnecessary files, follow the steps below based on the browser you're using.

How to delete cache in Safari:

  1. Open Safari, click on the Safari drop-down menu > Settings.
  2. Go to the Advanced tab and select the Show Develop menu in the menu bar checkbox.
  3. Open the Develop menu and then choose Empty Caches.

How to delete cache in Chrome:

  1. Open Chrome and at the top right, click three dots > More Tools > Clear Browsing Data...
  2. Check boxes next to Cookies and other site data and Cached images and files.
  3. Click Clear data.

How to delete cache in Firefox:

  1. In the menu bar at the top, click Firefox and go to Preferences.
  2. Select the Privacy & Security tab.
  3. In the Cookies and Site Data, click Clear Data.
    1. Check Cached Web Content, and click the Clear button.

      But there is an easier and time-saving alternative to clear browser cache: CleanMyMac X. Simply go to the System Junk module, press Scan, and then Review Details. Then click User Cache Files and press Clean. Done!

        CleanMyMac X - User cache files in System Junk module

        tip 5

        Remove Language Packs

        Most of your apps come with language packs (also known as localization files) that enable you to change the language in the app. It’s great to have this option, but let's face it: most people only need one language supported. Maybe two at most. The rest? They’re just wasting space.

        To delete language packs manually, follow these steps:

        An even faster way to remove language packs is to use CleanMyMac’s System Junk module. After running the scan, you can click Review Details and find Language Files. Click on it to see exactly what language packs will be removed. Once you’re happy with the selections, click on the big Clean button to further clear your startup disk.

        Mac running slow on macOS Ventura? Try this

        Many Mac users reported their Macs being slow after upgrading to macOS Ventura 13.0. This could be caused by software not yet optimized for Ventura. Still, there are some things you can try on your Mac to compensate for the Ventura slowdown:

        1. Clean up the Desktop clutter — this releases some amount of virtual memory.

        2. Update all your software.

        3. Minimize your login items in System Settings > General.

        4. Disable Dynamic Desktop.

        5. Use a couple of Mac speed-up tools in CleanMyMac X.

        The latest version of CleanMyMac X has added a set of tools titled “Speed.” You can do a lot of things, such as being able to free up RAM and heavy memory consumers.

        Download Free Version

        My Mac says there’s not enough disk space, but there is

        Sometimes, you can’t install an update because your system says there’s “Not enough disk space” while, in fact, you have that space available. This conflict could be attributed to the so-called “purgeable” space. It’s basically the space taken by all the unnecessary stuff that can be purged and converted into free storage. One way to free up your purgeable space is to disable iCloud drive optimization.

        1. Open your System Settings > Apple ID > iCloud.

        2. Check iCloud Drive and choose Options.

        3. Now, hit Turn Off.

        As you can see, iCloud backups were part of that “invisible” space on your Mac. It also helps if you empty your Trash — one more purgeable category of storage.

        When the available storage is not enough, Mac disk space can also be saved by removing the iOS backups.

        tip 6

        Clear system data storage

        Mac System Data includes macOS system and temporary files, app extensions or plug-ins, old backups, cache files (system cache, browser cache, etc.), and others. You have to be very careful not to do any damage to the system when trying to clear those up by yourself. If you have no idea what you're doing, then don't! Otherwise, use Finder to delete System Data files from the Library folder on your Mac.

        Follow these instructions to clear system data storage in Finder:

        1. Open Finder > Go > Go to Folder.

        2. Type in ~/library. Then press Enter. 

        3. Go through each folder to find files you no longer need. Right-click on a file and drag it to Trash.

        4. Empty the Trash. 

        tip 7

        Remove iOS Backups

        Do you own an iPhone or iPad? Have you ever updated those devices using your Mac? If the answer is yes, then you most likely have old backups taking up valuable space on your startup disk. The fastest and easiest way to delete heavy iOS backups is with macOS’ Manage Storage feature. Here's how:

        1. Apple menu > About this Mac > More Info Storage.

        2. Look for iOS Files on the list and select it. You should see a list of iOS backups in the main window, together with its size and the date it was last accessed.

        3. Select the backup you want to delete, then click Delete and confirm.

        4. Repeat for each of the backups you want to delete.

        Remove iOS backups

        tip 8

        Uninstall Unused Apps

        How many apps do you have on your Mac? Let’s be honest: how many of them do you actually use?

        Most people have at least a handful of apps that they never launched. You might think: so what? But these apps are wasting space, potentially even wasting other resources like RAM if running in the background.

        So, take a moment and have a look through your applications to see if there are some apps you can let go of and remove for more space and speed. Dragging them to the Trash will uninstall the app, but it will also leave behind lots of hidden files associated with the app, like app logs and crash reports.

        To see the list of all your unused apps and remove them completely, use CleanMyMac’s Uninstaller module. For a hard disk, it is a great startup cleaner that will free up all of the space that apps are taking up on your Mac.

        Unused Apps in Uninstaller module in CleanMyMac X

        Download Free Version

        tip 9

        Delete Duplicate Libraries from the Photos app

        If you made the switch to the new Photos app on your Mac, chances are that you’ve ended up with an old library that holds a bunch of duplicate pictures that take up space for no reason. It’s hard to understand why Apple chose to stick with this duplication after the upgrade. We can only assume it’s a smart way for them to convince users to buy more iCloud space. Whatever the reason, the good news is that now you’ll be able to easily remove the duplicate Photos libraries and clear up space. And this is exactly how to do it:

        Removing old photo library

        tip 10

        Limit Dropbox Sync

        If you are a Dropbox user, you need to be aware of the fact that Dropbox syncs everything onto your Mac by default. Look through your Dropbox folder and ponder whether or not you need all of those files and folders on your machine.

        Probably not.

        So here is how you can select which files and folders to sync in order to free up space on your startup disk:

        Dropbox Sync set up

        No more “Startup disk full” error message

        When wondering how to free up space on a Mac startup disk, it’s hard to tell where to begin. With these 5 essential tips and 5 bonus tips, you have everything you need to get rid of the “Your startup disk is almost full” message for good.

        Certain tricks like deleting cache with CleanMyMac and emptying your trash should become part of your routine. This way, your startup disk will be able to focus entirely on smoothly operating your Mac. So, bookmark this page and use these tips regularly to ensure the problem never returns.

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