Physical Memory vs. Virtual Memory

Discussion in 'macOS' started by Dj64Mk7, Oct 29, 2014.

  1. Dj64Mk7, Oct 29, 2014
    Last edited: Oct 29, 2014

    Dj64Mk7 macrumors 65816

    Sep 15, 2013
    This is something that's confused me for a long time.

    What is the difference between physical memory and virtual memory? Obviously, physical memory is the literal stick(s) of memory in our Macs.

    Virtual memory, however, is what confuses me. For example, I have 8GB of physical memory in my Mac. Activity Monitor says I also have 8GB of virtual memory. Does this mean that I essentially have 16GB of RAM? Or is virtual memory just another term for swap?
  2. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    This right here. It is just swap space on the drive used as temp memory storage.
  3. Dj64Mk7 thread starter macrumors 65816

    Sep 15, 2013
    Then why does Activity Monitor make the distinction between the two, like in the attached screenshot?

    Attached Files:

  4. chown33 macrumors 604

    Aug 9, 2009
    Sailing beyond the sunset
    One reasons is that virtual memory can be larger than physical memory.

    In theory, virtual memory can be smaller than physical memory, too, but there's no practical reason for doing that here.
  5. poiihy macrumors 68020


    Aug 22, 2014
    Virtual Memory is the combination of Physical Memory and swap space. It will always initially equal your physical RAM, but it grows as your system prepares swap space.
  6. Dj64Mk7 thread starter macrumors 65816

    Sep 15, 2013
    Basically V=P+S because swap is added to physical memory when it runs out.
    That makes sense, thanks.

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