Is your Mac running painfully slowly? Has an application just hung? Did you see a "Your system has run out of application memory” message or the dreaded spinning beach ball? All of these can be signs that your memory, or RAM, is being used to the max. Read on to find out how to clear the RAM on your Mac and various helpful tips to help you clean or optimise your Mac memory, including what to do if your Mac RAM is always full.

What is RAM?

First a quick primer. RAM stands for Random access memory and it provides storage for ongoing tasks and processes. The difference between the RAM and the rest of the storage on your Mac is that it’s faster, therefore your Mac is designed to keep certain things in RAM in order to speed things up.

Most Macs ship with 8GB RAM, although a few older models only have 4GB RAM. This may be plenty if you don’t run memory hungry applications and games, but even the most average user can come up against RAM issues due to memory hogging processes associated with badly designed web pages and apps.

If your Mac is using the majority of the RAM available you may experience problems such as:

Signs you are short of RAM

  • Spinning beach ball
  • "Your system has run out of application memory” message
  • Taking ages to load
  • Applications crashing

Unfortunately it’s difficult to upgrade RAM in a Mac, as you can see from this article about how to upgrade the RAM in a Mac. In some cases, upgrading RAM can be done, but it’s probably not the solution for everyone and we’d suggest that you try some of the tips below before rushing out and buying more RAM.

Another option is to download a third-party app that promises to optimise your RAM - we look at some such programs below. However, it should be noted that, in general, MacOS is capable of managing memory efficiently and deals with logs and cashes and the like itself, so you shouldn’t really need a third party app to do that for you. However, if it's a frequent problem you are encountering then it may well be worth looking at those options.

Before installing more RAM, or resorting to downloading an app, there are a number of things you can do that might free up your RAM and fix your Mac’s memory problems.

1. Restart your Mac

Restarting your computer is the simplest way to free up RAM. There’s a reason why the IT desk always tells you to “turn it off and on again,” most of the time it will solve your problem.

When your Mac restarts it will empty the RAM and any disk cashes, so when it starts up again you should find that things run smoother.

However, restarting your Mac may not be convenient. Perhaps your system has hung and you are afraid of losing unsaved information, perhaps and the idea of reopening umpteen apps doesn’t appeal, or maybe you are in the middle of something that you don’t want to interrupt (even if that is the process that is stealing all the RAM).

If you don’t want to restart your Mac what can you do to free up RAM? Read on…

2. Update macOS

Because it’s possible that your problem is related to a known issue with macOS, it’s always worth checking to see if you are running the most up to date version of the OS, and updating it if necessary.

We cover how to update the operating system software on your Mac here.

3. Check Activity Monitor

Our first port of call when our Mac slows down or an app freezes is to check Activity Monitor, an app that comes with your Mac. You can find it in Utilities, or just start typing Activity Monitor into Spotlight (press command + space to bring up a Spotlight window).

Activity Monitor will show you how much memory is being used and will help you identify if a particular app is using up more than its fair share of resources.

You’ll be able to see how your memory is being used in the Activity Monitor window. You’ll see details about each process and app, such as the amount of memory, how many threads, and so on. You can also add extra columns such as Energy Impact (handy if you are on battery power) by right clicking on one of the column headers. Below those columns you’ll see a graph for Memory Pressure, and data about Physical Memory, Memory Used, Cached Files, Swap Used. Next to that is a section for App Memory, Wired Memory, and Compressed.

As for what that all means, App Memory is what’s actually being used by apps and processes, Wired memory is what’s been reserved for apps and can’t be freed up, and Compressed is inactive memory that can’t be used by other apps. That will all add up to the Memory Used figure.

The Cached Files figure represents the unassigned memory that is available to you. (If you are wondering what Swap Used is, it’s the memory being used by macOS, so it’s already accounted for in the Memory Used calculation).

In the Memory Pressure section you will see a graph that gives an overview of how much pressure your system is under. Ideally the graph will be green, but if you are short of memory it will be yellow, or worse, red. It is possible that the graph will be red even if it looks like you have lots of memory available, so it can be a good indication of problems.

Here’s how to use Activity Monitor to stop memory hogging processes:

  1. Open Activity Monitor.
  2. Click on the Memory tab.
  3. Click the Memory column to sort processes by Memory usage. This will make it easier to see which process or app is hogging the RAM.
  4. When you have identified a suspect app, select it and click on Information (i) in the menu.
  5. This will give you some information about what is happening, including the memory being used by that particular process.
  6. You can shut down a process easily by selecting it in Activity Monitor and then clicking on the X which will force a process to quit. This doesn’t necessarily close the app. If it’s a web page causing issues rather than quit your browser it will just close and reload that page. On-the-other-hand if you were to quit a Photoshop process the application itself will close (and you’ll probably see a ‘closed unexpectedly’ warning.

Note: You shouldn’t close a process if you don’t know what it is as it may be required by your Mac.

4. Close suspect applications

If you glanced at Activity Monitor and noticed that certain apps appeared to be hogging resources even though you weren’t using them - maybe you didn’t even realise they were running, you may benefit from closing them down.

Even if you don’t look in Activity Monitor, a quick glance at your Dock could identify a few running apps that you could quit, thereby freeing up some resources. If you look at the Dock you’ll notice that some apps have a dot below their icon - these apps are open.

Here’s how to close an application:

  1. Right-click or control click on the app icon in the Dock.
  2. Click on Quit.

Speaking of apps that might be running in the background and using up resources, you can stop some apps from automatically starting up whenever you turn on your Mac, and this may also free up some RAM.

Here’s how to remove apps from your startup items:

  1. Open System Preferences.
  2. Click on Users & Groups.
  3. Click on your User name on the sidebar on the left if that’s not already selected.
  4. Click on Login Items.
  5. Here you may see a collection of applications that will open up every time you start your Mac.
  6. If you don’t need them to always be running, select an app in the list and click on the (-) button.

5. Check CPU usage

In terms of suspect apps, it’s not always just the RAM that’s being hogged by an app. Sometimes an app might be using a lot of processing power, which could have the effect of slowing things down.

Here's how to check CPU usage in Activity Monitor:

  1. Open Activity Monitor.
  2. Click on the CPU tab.
  3. Sort the processes by %CPU by clicking on that column header.
  4. Look for abnormal usage - if an app or process is using a high percentage of CPU it’s probably what is causing the issues.
  5. To quit that app or process select it and click on the (x) in the menu.

Perhaps a kernel_task is running in the background and taking up a lot of the resources. If that is the case you won’t be able to kill that process - this is because a kernel_task represents a collection of operating system processes. The only way to stop a kernel_task is to restart your Mac. However, it may be that the troublesome Kernel_Task is related to a hardware issue which needs addressing, and until you do you may keep seeing this reoccurring problem. In which case, you might want to run an Apple Hardware Test as described here.

Ways to maximise the RAM available

If you are struggling because your Mac doesn’t have a lot of RAM then there are a few things you can do to maximise what is available.

1. Tidy up your Desktop

If your Desktop is cluttered with documents, images, screenshots and the like, it’s worth tiding it up - or at least dragging everything into a Stuff folder. This is because macOS treats every icon on your Desktop as if it’s an active window, therefore the more icons you have littered around your Desktop the more memory will be used. We hope that when Desktop Stacks arrives in macOS Mojave it will go some way to address this issue.

2. Fix the Finder

When you open a Finder window what do you normally see? If you see All My Files or Recents then it’s worth changing this as all the information about the location of the files shown in that view will be stored in RAM. Open Finder and click on Finder > Preferences. Then under General choose a folder to be shown when you open a new Finder window. Once you’ve changed this destination you need to Relaunch the Finder. (Right-click on the Finder icon in the Dock while holding Option/Alt button and choose Relaunch.)

3. Shut web browser tabs

One of the websites you have visited may be a memory hog. Delete browser extensions - If you have installed web browser extensions it may be the case that one of them is the RAM guzzling culprit. To remove a browser extension from Safari, open Safari > Preferences, click on the extensions tab, choose the extension you want to uninstall, and click Uninstall.

4. Close or merge Finder windows

Another Finder related tip. As each Finder window can have an impact on RAM usage, either close Finder windows that you aren’t using, or merge all the Finder windows together. In the Finder, click on Window > Merge All Windows.

5. Make sure you have lots of free disk space

If you are running out of RAM your Mac’s drive can be used as virtual memory - so free up some storage space if you are running out of RAM. The recommendation is to keep 20% of your drive space free. You could delete large unused files, old downloads, and old apps.

6. Check the printer

Have you sent anything to print recently? It’s possible that a big print job is queued up and that has caused your Mac to hang.

7. Purge RAM in Terminal

We don’t recommend this unless you are an advanced user, but you could try opening Terminal and typing in: sudo purge. Then enter password and wait while inactive memory is cleared.

8. Delete Cache files

You could also try deleting cache files (again we don’t recommend this for beginners).

  1. Open the Finder and click on Go > Go to Folder
  2. Type (or paste in) ~/Library/Caches/.
  3. You may find files you can delete here - but be careful not to delete something your system needs!

9. Use an App to clear Mac RAM

As we said above, it shouldn’t be necessary to install a third-party app to manage your RAM as macOS should do a good enough job by itself. But if, for example, your Mac doesn’t have as much RAM as you’d like, then a third party app may turn out to be cheaper and less hassle than attempting to add more RAM yourself.

We’d advise that you use a tool from the Mac App Store as you can be confident that it is approved by Apple.

Here are a few of apps that you could try:

Parallels Tool Box

This app offers you more than 30 tools including a Free Memory tool. The benefit here is that you get loads of other handy tools such as Find Duplicates so you can delete things you don't need and free up space, an easy way to take screenshots and record video, and loads more.

When we ran it we regained more than 1GB memory. There’s a free trial available here, or it costs £15.99 a year.

CleanMyMac from MacPaw

With CleanMyMac X installed on your system you will get a Heavt memory usage alert if your Mac is running out of free RAM. Just click on the Free Up button to release some of the RAM and speed things up.

YOuc an find the Free Up RAM option in Maintenance tab of CleanMyMac X.

CleanMyMac also lets you see how if there are any Heavy Consumers - apps that are using a lot of memory. You'll find this in the Optimization section.


You can download it for free but some of the features require you to pay to unlock the full version. CleanMyMac costs £29.95/$39.95, you can download it here.

Memory Clean 2 from Fliplab

This will purge your Mac’s inactive memory - something you might want to do after closing a particularly intensive app or game. Some features are available via the free app but there is an in-app purchase to gain more tools. When we ran it is freed up about 1GB. Download it here.