Apr 10


When your computer is running a bit slowly, how can you tell if getting more memory will help?

If you run out of free memory then your computer will be forced to use some of your hard disk as memory, which is VERY SLOW because hard drives are much slower to access than your computer’s RAM.  Here’s how to check that you have enough RAM to stop this happening on any Macintosh running OS X. 

It’s not just a matter of saying ‘8 Gigabytes’ is enough because the amount of RAM you need will vary according to your computer and the programs you use regularly. Here’s now to check if you don’t have enough RAM.

How to check your Memory on El Capitan

With El Capitan Apple have introduced a very simple graph based on colours to let you know if you have enough RAM or not. Do this during the middle of using your computer for what you normally use it for. Don’t do this as soon as you start your computer as this won’t give a good indication of your normal usage. Better still, check it at various times over a few days.

  1. Go to your Applications/Utilities folder. (Click on your desktop so that the finder is active then hold down Apple-Shift-U, this will open your ‘utilities folder.)
  2. Open ‘Activity Monitor’ – it will probably be the top-most application in the Utilities Folder.
  3. Press Apple-1 to make sure that the main window of Utility Monitor is open.
  4. Click on the ‘System Memory’ tab at the bottom of the window. This will display a little graph with the memory pressure. It will look something like this:


If there is any red in the memory pressure you need more RAM.  Red means your performance is taking a hit because your computer needs to use the disk drive for memory.

If the memory pressure is green you have enough memory (like the screenshot above).

If the memory pressure is yellow it may be worth monitoring over a few days to see if it goes into the red.


Checking your memory on older versions of Mac OS

On older versions of Mac OS the display looks more like this:

There are two important items to take note of ‘Free:’ and ‘Page outs:’

Free tells you how much free memory you currently have available to use –  the higher the better.  If you have no free memory you should get more RAM.

A Page out  means your computer has run out of memory and had to use some of the Hard Disk instead of RAM. (This is the equivalent of your brain being too full so you have to write your thoughts down on paper to free up some headspace) This DRAMATICALLY slows down your computer.

Tip: Page outs occur when your Mac has to write information from RAM to the hard drive (because RAM is full).  Adding more RAM may reduce page outs.


Some Examples:

Here’s a mac with plenty of RAM (12G) – lots of Free RAM (green) and zero Page outs.

Here’s a mac with just enough RAM (8G) – a relatively little Page out Count (339MB) and some free memory (green).

Here’s a Mac that needs more RAM (it only has 640M!) – note the High Page Out Count (1010524) even though it currently has some ‘free’ RAM.

This Mac definitely needs some more RAM! Practically no free memory  AND High Page-out Count. (1GB!)  Performance will be suffering badly. I would add at least another 4G Ram, maybe 8G more to bring it up to 12G.

In OSX Leopard rather than giving a ‘count’ of page in and page outs, it gives a size in GB  of the amount of RAM that has been paged in or out. The numbers are smaller but the same principals apply.

In OSX Lion there is a new entry called ‘Swap Used’. (See the last picture above). This  is a count of how much Disk Space your computer is using as RAM and it’s a good rough estimate of the minimum amount of  extra RAM you need. Eg If your Swap used is 4G then get AT LEAST 4G more RAM.


Where to buy more RAM.


Currently my favourite place to buy RAM is Crucial.com. My Mac mini has 16GB of Crucial RAM in it at the moment. Crucial have good prices and reliable RAM. I’m in Australia and it usually arrives in about a week.

They have a memory lookup tool for all computers where you choose your model and it shows you exactly what memory you need.  The memory chooser tool looks like this:

First choose ‘Apple’ where it says ‘Choose Manufacturer’

Secondly select your mac when it says ‘select product line’ (e.g. iMac or Macbook etc)

Finally select the exact model (e.g. Early 2011 i7 27″ iMac”)

It will then show you the options you can buy.


Another reliable source of good Mac RAM  is macsales.com. I have signed up to be an affiliate of Macsales.com so I get a commission if you purchase from them, but check the prices first because macsales can be more expensive.

Why RAM affects your computer’s speed.

RAM in your computer is like the paper sitting on your desk. The information is easy and fast to access. Your Hard Disk is more like a filing cabinet, it takes a bit longer to retrieve information.

When your desk gets too cluttered you need to spend some time moving things in and out of the filing cabinet, which slows things down.

You don’t need to be able to store everything in your computers memory, it’s good to have a hard disk, but if you don’t have enough memory then your computer will need to access your hard disk too much and this can slow things down.

To quote from Apple:

Moving data from physical memory to disk is called paging out (or swapping out); moving data from disk to physical memory is called paging in (or swapping in)… Extended periods of paging activity reduce performance significantly; such activity is sometimes called disk thrashing.

123 Responses to “Does my mac need more memory?”

  1. Joliepop says:

    I am dumb as dirt and I was able to read and understand this article. Your screen captures were great! I was able to match w/my Activity Monitor and I still might bring my Mac to the Genius Bar but at least I am more informed that I need RAM. Thanks so much!!!

  2. Geno says:

    Great article, but I have a MacBook Pro5.5 (late 2009), running Mavericks, and the Activity Monitor doesn’t have tabs at the bottom. I’m not seeing anything about Free and Page Outs, so I wonder if something changed with Mavericks? How can I ascertain that same information? It does show Physical Memory (4GB) and Memory Used (about all of it), but I’d like to ensure upgrading my memory is going to have a positive impact on my system performance, which has become progressively worse.

    • Ally says:

      I have the same issue as Geno and JoJoHants with the difference layout – does anyone have any information about how we can get the one with the charts and the mention of Free and Page Outs?

    • Michelle says:

      Did you ever get an update on this? I have macbook late 2009 as well and not seeing the page in or out info.

  3. Brenda says:

    Tks, : ) love this site so easy to get an answer & understand. Dont leave here thinking did that help me or not. Graphs really break it down 2 simple. Marking this site FOR SURE (I’ll B BACK)

  4. Phil says:

    Hi my memory slot says ” PHYSICAL MEMORY 4.00 GB

    Now I’m confused, though my computer does say’ system overload’ in new Garageband 10.3.

    Any help appreciated very much, thanks a lot :)

  5. Hiran says:

    Hi, the approach is really appreciable, but can we have some demo on EI Captain too, as its not using the same words in activity monitor.
    Thank You.

  6. Cathy says:

    Thank you for this helpful post. I am showing green in the graph for physical memory so it seems from your post that I do not need more ram. And I have fib optics yet my Mac is running so slowly. What else should I check for? Thanks.

Leave a Reply

Copyright © 2013 Wayne Connor. All rights reserved. | Hosted on bluehost.com Click here to find out why.