Making The Most of Activity Monitor

Many Mac users likely haven’t even opened this application before, and those that have were probably scared off by all the numbers and confusing words. I certainly was. But if you understand how it works and what it can be used for, Activity Monitor can be a great way of keeping an eye on what’s going on inside your computer.

This how-to will explain all the ins and outs of Activity Monitor, and how to get the most out of it. It will also give you some tips on how to speed up your computer a bit.

The Interface

Activity Monitor can be located inside the Utilities folder, which is in the Applications folder on your computer. Fire it up, and you should see a window similar to the one here.

The Interface

The Interface

Activity Monitor is a great application to find out if something is really slowing your computer down. To understand your way around Activity Monitor, I’ll let you know what all of the various buttons along the top do:

Quit Process

This button is used for when an application or process is slowing your computer down a lot and you need to kill it. You’ll probably know that you can already force quit stubborn applications for the Force Quit menu found under the ‘Apple’ logo at the top of your screen. However if there is something you can see here that doesn’t usually show up in that menu, you can select it and hit the ‘Quit Process’ button. Make sure you carefully read the dialogue box that pops up, and make sure you never quit something unless you know what it is.


Use this button to find out more information on a selected process or application. This basically gathers all of the information found in the button bar at the bottom and groups it for the selected process. It also contains some other advanced information that only a programmer would probably be able to understand.



Sample Process

Used for finding out specific information on what a process is performing at that time. This is pretty confusing unless you can read code.

Pop Up & Filter

This is actually surprisingly useful. By default, it should be set to “All Processes” which will show you everything. If you change it to “All Processes, Hierarchically”, it will list them so that if one process was created by another, you can see that. This is important because if you quit a parent process, you could also loose other important processes. Have a look through the other options as well for different ways of sorting them. The search Filter is just used for searching for a specific process.

Processes & Applications

All of the important information on processes can be found in the very center of Activity Monitor. You’ll probably notice, depending on what you are sorting by, that the list keeps changing. This is because the processes and their tasks are continually changing while your machine is running even if you aren’t doing anything.

To add or remove columns just right click on the top of them and tick the ones you want. Here’s how to decipher all of the main columns:

Process ID

This is a number assigned to every process and application that runs on your computer, and as a new process is initiated, it is assigned a new number in increased value. This is particularly useful if say you’ve noticed that your computer has suddenly slowed down dramatically. You could sort by Process ID (by clicking it’s header) and the processes at the top should be the ones last opened.

Process Name

This is the name of the process. The names don’t always clearly refer to the actual process though, so don’t mess around with any you aren’t sure about.


This lets you know what percentage of CPU each process is taking up. Usually, this shouldn’t be too high unless you’re performing some intensive tasks. To see what I mean, open iTunes. After it’s finished opening up, the CPU for it should be 0 or close to it. Now start playing some music. You should notice that the CPU jumps up to around 4. Now start the Visualizer. These are very intensive on your computer, and so depending on the one you’ve got running, the CPU should jump massively to somewhere around 90. Maybe thats a good reason not to use visualizers if you are trying to use your computer at the same time.

Real Memory & Virtual Memory

This is the amount of RAM (real memory) and artificial RAM (virtual memory) being used up by each process. Real memory is much faster than virtual memory, but virtual memory is created to perform multi-tasking.


This tells you under which user the process is being run. Useful if you have multiple accounts logged in. Any unusal usernames such as ‘root’ are simply system ones.


This tells you whether the process is Intel or PowerPC

The Buttons Bar

Down the bottom of Activity Monitor you can find useful information on the system as a whole.

The CPU graph shows you how much of the CPU you and the system are using up on the computer. If you want to see a larger graph of this, in the menu bar go: ‘Window’ > ‘CPU History’.

System Memory

System Memory

The System Memory gives you a nice pie chart of how your RAM is being used. It’s fairly self explanatory, but ‘Wired’ memory is “information that can’t be cached to disk, so it must stay in RAM. The amount depends on what applications you are using” according to Apple.

Disk Activity is not so useful for the ordinary user, but Disk Usage is helpful for viewing how much space you’ve used up on any Hard Drive or USB stick for example.

Finally, Network lets you know how much data is coming in and how much is going out. For example, if you are streaming a video you should notice that the Data Received/Sec (in green) will be quite high.

The Dock Icon

One clever feature of Activity Monitor is that you don’t even need to have the window open to get an idea of what’s going on inside your computer.

Just right click on its icon in the dock, and under ‘Dock Icon’ tick one of the different options. My favourite one is ‘Show CPU Usage’, as this gives you information on how much each of the processors on the computer are working.

The Dock Icon

The Dock Icon

You can also get a floating window of the CPU Usage if you’d like it. With Activity Monitor selected, in the menu bar go: ‘Window > Floating CPU Window’.

If you would like to have a quick overview of this information, there are also dashboard widgets such as iStat Pro which may be suitable.

Example Use

One of Activity Monitor’s most useful features is simply the ability to Quit processes. If you’ve been noticing that your computer has been lagging a lot lately, you may wish to take a look inside and see if you can spot anything which might be causing it.

Any processes which show up in red means that they are not responding, and, if they’ve been like that for a while may need to be killed. You may have had the Dock freeze up on you before. If this happens, it may help to restart it by using Activity Monitor. Another example of a good reason to quit a process is if it’s taking up too many of the systems resources.

For example, if you take a look back at the first image of Activity Monitor’s interface, you’ll notice that at the very top of my CPU usage is ‘HP Communications’, consuming 52.4% of my CPU! This could well have been one of the reasons that my computer has been running rather slowly lately, if its constantly using that much. It’s obviously the connection with my HP Printer, and I have no print applications presently open so there is no reason for it to be so high. For this reason, and because I felt confident that I knew what it was, I selected it, and pressed ‘Quit Process’. My printer still prints fine without it running, but that has freed up my resources a lot!

Have a look yourself and see if there’s anything you can do to speed up your computer. Again, make sure you don’t mess with anything you don’t know about though!


As you can see, Activity Monitor can be a little confusing, but with the right understanding it can boost your computers performance and help you work out what’s causing problems, and which applications and processes have the most impact on your system. It certainly can make a difference, as I’ve found after quitting the HP Communications process!

Let us know any tips for using Activity Monitor that you’ve found useful, or how you use it on your Mac.


Add Yours
  • Very good post. I think that Activity Monitor have lots of feature and that it is very usefull.

  • great post for me as a new mac user :) thanks a lot!

  • Nice post… but still not gonna use it though haha :D

  • Can you use this program to quit certain functions inside Photoshop? For example, if I’m applying a filter to a photo and I decide I don’t want to use the filter anymore (because it’s taking too long) can I use Activity Monitor to see that particular action in Photoshop and quit it?

    • Hi Jonathan. I’m afraid you most likely won’t be able to do that. That’s because when Photoshop is applying a filter, it’s still Photoshop performing this, not some other application or process.

      If you have Activity Monitor open while performing a filter, you should notice the CPU for Photoshop skyrocket to some huge number as it tries to perform this for you.

    • You can just press the escape key while applying filter, it should cancel the operation.

  • I am a recent convert from windows to mac. The task manager equivalent was what I was looking for. As usual the apple equivalent is far smarter than Windows. Thanks for this info.

  • i copied a file from my mate’s usb onto my mac. and it literally has still been copying for weeks. and i’ve removed the usb and everything, and it’s still going ! the worst part about it is that i can’t shut down my mac, as it won’t allow me to shutdown unless all applications are closed, which i can’t as the file is still copying.
    i used activity monitor to close the process, but i accidently quit dock instead.
    and now everything is so hard to use.
    how do i get the dock back down the bottom of my screen ?
    and how do i end the process of copying that file !
    i’ve tried researching it but have been unable to find it. and technical support is closed over the weekend. i’d like to try and fix it before next week.

    • I should hope you’ve discovered how to shut down your computer by now, almost three years later, but for other readers: hold down the power button until the computer shuts down. Rule No. 1.

  • great write up on the activity monitor. it’s the best program to drill down to the process you want to quit. one question though, in the dock section, is there a way to ‘really’ get all the monitors to show up at once. if there is a way, which i never found (it’s a choose one scenario), then all other process monitor apps would be dropped for me. ^_^

  • I quit an process before reading this post. It was something to do with safari and or flash player. Now when I try to watch video on the internet it is very slow. I unfortunately do not know exactly what I quit. Is there a way or a log per say that will tell me which processes I quit or altered? And if so, is there a way to rejuvenate the process? Thank you so much for any help you can provide.

  • hi, can i use your photos in this article in a presentation that i have?

  • My Mac is running OS X 10.6.6, and I am having problems with the MicroSoft Office 2008 Suite. Quite often the “Rainbow Circle Of Death” will pop up, and then I am frozen out of that application, and sometimes I am also frozen out of other applications, such as Safari, etc. I was thinking of adding memory, however the Activity Monitor shows a very low usage of memory. (I presently have 4G of DDR3 RAM installed.) Any suggestions?

  • On my work boss is using kind of monitoring employee software. It calls ActyMac DutyWatch.
    Do you know something about it?

  • This article really doesn’t help very much. It gives you the obvious basics, but what is more important are the numbers at the bottom of the Activity Monitor window and what the mean. For example, when you click on the Network tab, you see one called Data Received which doesn’t explain from when, and seldom changes. The same thing for the one called DataSent. Also the moving graph acts kinda squirrely. It might show a very small activity going across the screen, but when it gets to the left, it jumps to maximum. The timing that it happens only as the screen rolls to the left is odd. It appears as if it re-calibrates the max showing on the screen constantly, so you have no real reference point. It would be nice to have a way to turn that off, or at least show some numbers representing what the present scale represents. My real goal for using this is to see if anyone from the LAN or WAN are accessing my computer slowing things down, or doing things that I do not want done to my computer. It is bad enough that app updates send you updates that restrict what you do, so they make more money. But to not know who are when someone is accessing your computer can be scary.

  • I just recently used this program and deleted a program i need to use agian but i didnt know what it was, is there anyway of getting it back? It was a flash player plug in used with my safari.
    or is there another way of getting it back.

    Stupid thing to do really.


  • I was watching a video on how to quit things using activity monitor, and saw applications i didn’t know, so i decided to quit some of them. But as I deleted one, it said are you sure you want to quit this and all that stuff, so I just pressed force quit.
    But the next thing I know, my computer shuts down. I try to restart it, but it’s now stuck on a black screen with only the mouse visible (which i can move). I can also up/down the sound and brightness, but I can’t turn it off. What should I do?