Understanding Mac OS RAM Usage, How Mac Computers Use Their RAM

Understanding how Mac OS X uses its RAM is a very good thing to know if you’re an avid Mac user. It can be helpful if your computer is responding very slowly, your computer feels hot, or, if you already know a bit about RAM, you can learn how to free it up. Have you been told, or have been considering buying additional RAM for your Mac computer?  It is expensive, and it may not even be necessary. Read on to increase your understanding on Mac OS RAM usage.

You can view all sorts of information about your computer’s RAM and how it is being handled by opening up your Applications folder, then your Utilities folder, and clicking on Activity Monitor. You should end up seeing something like this.


This is your Activity Monitor. Similar to Windows’ Task Manager, here you can view running processes, and most importantly, how much RAM memory is being allocated to them.

Take note of this part right here.

As you can see, the RAM is divided into four parts. Free, wired, active, and inactive.

Active Memory

Active memory is the memory that is currently being allocated to running applications.


Inactive Memory

Inactive memory is memory that was used by an application you had recently closed. Mac OS thinks that if you close an application, you may be likely to reopen that application again very soon. This is based off of the idea of temporal locality. When an application is launched, it is loaded from your hard drive and into your RAM. By having this inactive memory, it allows recently closed applications to reopen extremely fast. You can try this by opening an application you haven’t opened in a while, and when it finishes launching, exit out of it. Then relaunch the same application, and it’ll launch almost instantly. Take note that this shows in Activity Monitor as the lowest section on the chart, only ~1/40 of my total RAM in my example.


What Is Wired Memory?

The other names can seem self explanatory to some people, but it’s more difficult to understand what wired memory is just by reading it’s name. Wired memory is simply the memory that your computer’s kernel and system drivers use. This type of memory can not be used by any sort of application. Although it may fluctuate, a user can never manually add or remove wired memory.


Free Memory

Free memory is memory that is not currently being used for anything. Any application can take free memory and use it, turning it into active memory. If your computer is extremely low on free memory, it will take memory from the inactive memory slot and assign it to applications that need it.


How do I get more free memory?

You can get more free memory by ending processes that are using a high amount of RAM. The higher the number in the “Real Memory” column in Activity Monitor, the more RAM that application is using. If you find yourself constantly having to end processes just to keep your computer responding, it may be time to purchase more RAM.

How To Check Your RAM

You can find out the type of RAM your computer uses by clicking the Apple logo at the top left of your screen, and clicking “About This Mac”. It is extremely important that you get the exact same type of RAM that’s made for your computer.

Got any questions? Email me at questions@techpopper.com, or post a comment and I will try to get back to you as soon as I can. Thanks for reading!

One thought on “Understanding Mac OS RAM Usage, How Mac Computers Use Their RAM”

  1. Using a program like Memtest86 is a good way to “Check your RAM” – to see if it is all in working order. It is a free program too! I was a little confused by that title, and did not really have an explanation – maybe it should be “How to check what type of RAM you have” – another good suggestion here might be to use an online memory configurator if you do not have a Apple computer, or are having problems following those instructions. Quantum Technology has quite a large database of computer systems and of course they have apple memory upgrades

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