Mac OS X: How to View Memory Usage With the "top" Utility

You may use the top utility in a Terminal window to monitor the usage of RAM, virtual memory, and CPU cycles, in addition to other statistics.
This article has been archived and is no longer updated by Apple.
This article offers an advanced technique. You may perform similar monitoring with the ProcessViewer application. For information on using the ProcessViewer for this task, please see technical document 106386: "Mac OS X 10.0: How to View Memory Usage and Installed RAM"

Viewing memory usage with top
    1. Open Terminal (located at /Applications/Utilities/).
    2. Type: top  
    3. Press Return to open the top utility in the Terminal window. Two rows near the top of the window, "PhysMem:" and "VM:" indicate overall physical RAM and virtual memory usage, respectively. The two columns on the right, "RSIZE" and "VSIZE" offer memory usage information per application. RSIZE indicates the amount of physical RAM in use by the application or process, in megabytes ("M") or kilobytes ("K"). VSIZE indicates the amount of virtual memory Mac OS X has assigned for this process or application, in megabytes ("M") or gigabytes ("G").
    4. When you are finished reviewing the information, press the Q key to exit top.

    1. Application and process names are listed in the "COMMAND" column.
    2. It is normal for some processes to use very little RAM, such as 64K.
    3. Not all applications may have an easily-recognizable name in the Terminal window. For example: Microsoft Internet Explorer 5.1 appears as "Internet E."
    4. As with Process Viewer, Classic applications do not appear individually in the Process Listing window. It is normal for the Classic environment to appear as a single process (TruBlueEnv).
    5. top itself is listed because it is an open application. This is normal.
    6. Type "man top" in the Terminal for more information on top.
Published Date: Feb 17, 2012