What you need
- Multimeter for macOS 13 or later, $19.99 once.
- The direct download version of Multimeter from this site (the Script source isn’t in the Mac App Store version).
Set it up
- Try the command in Terminal. It prints the busiest process as a small JSON object:Command
ps -Aceo pcpu=,comm= -r | head -1 | awk '{p=$1; $1=""; sub(/^ +/,""); gsub(/"/,""); n=substr($0,1,14); sub(/ +$/,"",n); printf "{\"value\": %s, \"label\": \"%s\", \"unit\": \"%%\"}\n", p, n}' - Add a meter with the Script source and paste the command.
- Set Refresh every to 5 seconds, the range to 0 to 100, and alerts to High values: warning at 80, critical at 100.
- Pick a face that shows its label, like Label & Value, and drag Width to 120 pt. The label the command sends replaces the meter’s own, so the menu bar shows the process name. At the default width only short names fit, and the face hides a label that doesn’t fit.
Multimeter settings
In Customize This Meter… (from the meter’s menu):
| Setting | Value |
|---|---|
| Source | Script |
| Command | the ps line above |
| Refresh every | 5 seconds |
| Range | 0 to 100 |
| Alerts | High values: warning 80, critical 100 |
| Face | Label & Value |
| Width | 120 pt |
Tested: Set up on October 31, 2026 in Multimeter 1.1.1 on macOS 27. With an Apple Archive compression running, the menu bar showed aa 399% in red. With one busy Google Chrome Helper process it showed Google Chrome 100%, and the memory version showed dd 1.4 GB during a 1.4 GB copy.
Script meters need the direct download version of Multimeter from this site, which is the one on sale now. How commands run, the PATH they see and the 10 second limit are in the Script meters guide.
Limits
- Percent is counted the way Activity Monitor counts it: each core is 100%, so a busy process can show 150% or 400%. 100% means one whole core.
psreports a short running average, so a process that just started or stopped takes a few seconds to move.- Names are the short process names
psgives (Google Chrome Helper, WindowServer, mds_stores), the same as Activity Monitor’s Process Name column. The command keeps the first 14 characters so the name fits next to the value, so Google Chrome Helper shows as Google Chrome.
Variations
Busiest by memory
Sends gigabytes in use, with the name as the label. Set the range to your Mac’s memory, like 0 to 16.
ps -Aceo rss=,comm= -m | head -1 | awk '{m=$1/1048576; $1=""; sub(/^ +/,""); gsub(/"/,""); n=substr($0,1,14); sub(/ +$/,"",n); printf "{\"value\": %.1f, \"label\": \"%s\", \"unit\": \"GB\"}\n", m, n}'Watch one app
Replace head -1 with grep -m1 Safari (or any name) to follow one app’s CPU instead of whoever is on top.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| The script didn’t print a number | The command failed or printed an error message instead. | Run the exact command in Terminal. If it works there, check for tools that live outside the meter’s PATH and use their full path (which tool). |
| The script took longer than 10 seconds | A slow network call. Multimeter stops scripts after 10 seconds. | Keep the -m timeout on curl, and refresh less often. |
| Scripts need the version from multimeterapp.com | This copy of Multimeter came from the Mac App Store, which can’t run scripts. | Use the direct download version, or run the command from cron or launchd and point a File meter at its output. |
| The name never shows, only the number | The face doesn’t show a label, or the meter is too narrow for the name. Label & Value drops a label that doesn’t fit. | Pick Label & Value in Customize and set Width to 120 pt. |
Questions
Does this work in the Mac App Store version?
Script meters need the direct download version from multimeterapp.com, because the App Store sandbox doesn’t let apps run your commands. Web Address, File and Sent Value meters work in every version.
Does the CPU meter show this already?
No. The CPU meter shows a total across all cores. This recipe adds a second meter for the single busiest process; use both if you want the total and the name.
What do process names like WindowServer or mds_stores mean?
They’re parts of macOS. See WindowServer, mds_stores, kernel_task and Google Chrome Helper.