How to check CPU usage on a Mac from Terminal
top, ps and a one line command show total and per process CPU on a Mac. Ours was 10% user, 13% system, 77% idle. Why one app can show more than 100%.
Total CPU use
top -l 2 -n 0 | grep 'CPU usage' | tail -1Ours printed CPU usage: 10.30% user, 12.52% sys, 77.16% idle. User is apps, sys is the kernel working for them, idle is spare. Use the second sample: the first has no previous reading to compare with.
Which process uses the most CPU?
top -o cpu -n 10
ps -Ao pcpu,pid,comm | sort -nr | head -10| Process on our Mac, one moment | CPU |
|---|---|
| kernel_task | 66.8% |
| WindowServer | 65.0% |
| apsd | 2.5% |
| NotificationCenter | 2.0% |
Why does a process show more than 100%?
Per process CPU counts one core as 100%. A process busy on three cores shows 300%. Our M1 has 8 cores, so 800% is the ceiling for one process.
See it live
Free Mac's System tab reads processor, memory, network and battery once a second, with the busiest processes ranked below, and every tile opens into detail. See also load average and kernel_task.
Related: check disk activity and check your Mac's uptime.
Common questions
How do I check CPU usage in Mac Terminal?
Run top -o cpu, or top -l 2 -n 0 | grep 'CPU usage' for the total.
Why is a process using more than 100% CPU?
Per process CPU counts one core as 100%. A process on several cores goes above it.
How do I find the process using the most CPU?
ps -Ao pcpu,pid,comm | sort -nr | head lists the top ten.