Here is a screenshot of Activity Monitor network usage tab. Look at the Data Received total at bottom, and then look at the process amounts in the list on top. It doesn't add up.

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1 Answer 1


As far as I'm aware, one value is 'since you opened the window to start logging' the other is 'since last boot'.
Example much, much greater discrepancy…

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  • I see. If so, it makes Monitor a bit less useful than I thought it was :-P I'll check your answer as definitive unless someone contradicts you. Thanks.
    – q.undertow
    Oct 19, 2022 at 1:06
  • I'm not certain the exact point from which the columnated data is derived. I leave Activity Monitor running all the time, it auto-launches at boot, yet I rarely look at this particular tab. So, the values you see above are for 4 days' uptime for the whole machine, with 10s of that tab being in view. If it were strictly from the time I opened the tab, you'd expect most of those values to be near nil, which they're not, even though they're small.
    – Tetsujin
    Oct 19, 2022 at 6:47

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