How to clear application memory on Mac

macOS is based on Unix, meaning its memory management is pretty robust. However, it's not perfect, so you may still see an error message saying, "Your system has run out of application memory." What does it mean, and why does it happen? We'll explain what causes the error and what to do to fix it. 

What is application memory on Mac?

First, let's find out what application memory is. Simply put, it stands for the part of your macOS that is responsible for handling running applications. Do not confuse it with Mac storage, though. When you download an app, it goes to your Applications folder and is stored on your Mac's hard drive. But when you start using any app, it uses memory — RAM.

What does "your system has run out of application memory" mean?

macOS stores data used for active processes in RAM. If space in RAM runs low, macOS starts storing data on your main boot drive and swapping it between there and RAM as needed. This is known as virtual memory. For this reason, you should always have a decent chunk of free space on your boot drive — 10% is a good rule of thumb. If you don't have enough space on your boot drive for an application to store temporary files, you will see the error message telling you your system has run out of application memory.

Why does it happen?

There are a number of things that can cause this error message to appear, although, as we said, macOS memory management is very good, so if you do see the message, you should take action.

Reasons include:

The best way to avoid seeing the error message is to make sure you keep as much memory as possible free on your Mac. An Apple-notarized Mac app, CleanMyMac, has a handy Menu that makes it easy to monitor application memory and free it up anytime you feel like your Mac slows down. Here's how to use it:

1. Download CleanMyMac for free here. 
2. Install and open the app.
3. Go to your menu bar and click the CleanMyMac icon.
4. Click Memory.

Your Memory monitor will appear on the left. Here, you can control how much memory you have available and quit top memory-consuming apps. You can also free up your memory right here — click Free Up in the Memory section to fix all memory issues on your Mac. 

How to check application memory on Mac?

Before freeing up application memory on Mac, you may want to know how to check it. Luckily, there is a built-in tool designed for the job — Activity Monitor. 

Here's how to use it: 

1. Go to Applications > Utilities. 
2. Open Activity Monitor.
3. Click Memory and check the data at the bottom of the window. Pay close attention to App Memory next to Memory Used.

How to fix the "Your system has run out of application memory" error

There are other ways you can tackle the problem, too.

1. Restart your Mac

This is the first thing you should try. Restarting your Mac clears the cache and other temporary files and gives back disk space used as virtual memory. Go to the Apple menu and click Restart.

2. Update macOS

Whenever you run into problems on your Mac, it's a good idea to check if there is an update available in case the problem is a bug and there is a fix for it in the update.

1. Click the Apple menu and choose System Settings.
2. Select General > Software Update.
3. If there is an update available, follow the instructions on the screen to install it.

   

3. Close apps you're not using

Keeping apps running in the background when you're not using them eats up a lot of virtual memory. It's a good practice to quit apps when you stop using them. Press Option-Command-Esc to open the Force Quit menu. If there are programs you're not currently using, quit them.

4. Clear disk space

Users on forums agree that being low on disk space can be one possible reason why Mac runs out of application memory. As we've already mentioned, it is a good idea to have at least 10% of your disk space free. So, if you have a Mac with 512GB drive, strive for more than 50 GB of free space to have your computer run flawlessly. 

But how do you free up storage on Mac? Go to System Settings > General > Storage and click each category under the colored graph to see what can be deleted. 

If it sounds like a lot of work, there's an easier way to get rid of unneeded clutter — CleanMyMac. It has a smart Cleanup tool that allows you to remove all unnecessary junk files, thus freeing up the System Data in your storage. All you have to do is click Cleanup > Scan > Clean.

It also has the My Clutter tool that helps you find the largest and oldest files, similar photos, and duplicates. By using CleanMyMac, you will free up gigabytes of storage in no time. Download it for free here and give it a try.

5. Update apps

As with macOS, it could be that one or more of the applications you're running has a bug that causes it to hog memory. You should check whether there are updates available for those apps because any bug is likely to have been addressed in it. For apps downloaded from the App Store, you can do that on the App Store. All you have to do is follow these steps:

1. Open the App Store from Launchpad, Dock, or the Applications folder
2. Click Updates.
3. If any updates are available, click either Update or Update All.

For other apps, click the app's name on the top-left corner of your screen — there should be a "Check for Update" option.

6. Close browser tabs

Modern web browsers can have so many tabs open simultaneously that many of us spend all day with dozens of them open. And then we wonder why our Macs are running slowly. Keeping tabs open means they update in the background, taking up memory and other system resources. Bookmark tabs you use regularly and close them when you're finished using them.

7. Uninstall applications

Some applications take up several gigabytes of space on your Mac, so if you don't use them, it makes sense to uninstall them. If they were downloaded from the App Store, you could always download them again when you need them. Or, if not, you should be able to re-download them from the developer's website. Did you know, for example, that Microsoft Word takes up to 2GB of space? So, it's better to get rid of unnecessary apps.

There are several ways to uninstall apps on Mac:

1. Delete an app via the App Store. If you've downloaded it from App Store, open the Store, click your user name at the bottom, and find the app you want to remove. Now, click the ellipsis button and choose Delete App. Confirm it.
2. Drag an app to Trash from the Applications folder. Don't forget to empty the Trash afterward.
3. Use Launchpad. In this case, all you have to do is find the app via Launchpad, click and hold it until it starts shaking, and click X > Delete.

   

4. Run a native uninstaller that comes with some apps. It is found in the Applications folder and named [App] Uninstaller or Uninstall [App].
5. Use CleanMyMac and its Uninstaller tool — it quickly finds all app-related files and removes them in one go. Just open CleanMyMac, go to Applications, and click Scan > Manage My Applications > Uninstaller. Now, select an app (or several apps at a time) and click Uninstall.
   

Note that unless you used CleanMyMac, you will need to hunt down leftover files to make sure that you completely removed the app. To learn more on how to delete app leftovers, read this article.

8. Reduce the Finder's memory usage

Commonly, memory-related issues have to do with the Finder. It is a native file manager that helps you browse the files and stores paths to all of the files you have on your Mac. The process is RAM-intensive, though. So, if nothing has helped so far, you may want to limit its memory usage. Here's how:

1. Open a new Finder window.
2. Select Finder > Settings from the menu bar.
3. In the General tab, find the 'New Finder windows show:' dropdown.
4. Select a location different than "Recents" or "All my files."

   

5. Press and hold the Option key and right-click the Finder icon from the Dock.
6. Select Relaunch.

9. Use Apple's Storage Management

Apple provides some useful tools to help you manage space on your boot drive.

1. Click the Apple menu and choose About This Mac > More Info.
2. Choose Storage Settings.
3. Check Recommendations, and you will see a list of things Apple recommends you do to free up storage space. Decide which recommendations you want to take and follow the instructions.

10. Install more RAM

The last resort, and the most expensive option, is to install more RAM in your Mac if you can. Having more physical RAM will mean macOS needs to use your boot drive less often to store swap files. However, not all Macs can have RAM upgraded after purchase, and for those that do, it usually means a trip to an Apple Store or an authorized service center.

How to reduce memory usage on your Mac using Activity Monitor

If you've completed all the steps above and are still getting the same error message, you'll need to do some detective work to track down the source of the problem. macOS has a great tool for this work — Activity Monitor. It allows you to see all processes currently running on your Mac and list them according to the system resources they are consuming, including RAM. In this way, you can see which processes are hogging memory and possibly causing the error message, then quit them.

1. Go to Applications > Utilities and open Activity Monitor.
2. Click the Memory tab to see a list of processes that consume memory, including applications and browser tabs.
3. Select a process or app and click the "X" sign to close it.
Tip

The app we mentioned earlier, CleanMyMac, has a Performance tool to help you quickly optimize your Mac. It flushes DNS cache, reindexes Spotlight, repairs disk permissions, and does so much more to keep your Mac's system running smoothly.

There are many reasons you might see an error message telling you that your system has run out of application memory. But they all point to the same thing — a shortage of space on your boot drive. So, the simplest solution is to free up more space. However, you should follow the steps above to identify whether there is a problematic app taking up more memory than it should.