I ran a Java applet, and it used over 200% of my CPU....

%CPU 273.5

It actually rose to over 400% after I took the screenshot.

How is this possible? Can someone explain why Activity Monitor shows a task as using more than 100% of my CPU?


1 Answer 1


The CPU percentages shown in Activity Monitor are 100% for each virtual core. If you have a quad core processor with hyperthreading, 'real' 100% is 800% in Activity Monitor.

  • Is this because of hyper threading that each core gains up to 200% per core?
    – pronebird
    Commented Jan 23, 2018 at 13:12
  • How can I find out what my maximum activity monitor CPU% could possibly be?
    – minseong
    Commented Apr 18, 2023 at 17:36
  • I've never seen higher than 400 in Activity Monitor, but when I open the CPU History Window there are slots for 8 cores and all of them have some activity (although the cores labelled 2, 4, 6, and 8 have almost no usage)
    – minseong
    Commented Apr 18, 2023 at 17:38

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