# Unmeasured processes

Canonical page: https://vitalsmac.com/glossary/unmeasured-processes

Activity Monitor glossary, CPU, GPU and energy. Why does the process list add up to less than the total?

Also: why the list doesn't add up to the total

**Short answer:** The processes in a system monitor rarely add up to the total in its graph. In Activity Monitor that is because each core counts to 100% and work between two samples is missed. In other monitors it is also because macOS lets an app measure only the processes that belong to your user, so system processes such as WindowServer and kernel_task stay blank unless a helper reads them.

Two different things are going on, and it helps to keep them apart. The first is arithmetic: Activity Monitor's % CPU column is a share of one core, so on an 8-core Mac the column can add up to 800% while the graph at the bottom shows a percentage of the whole machine. Divide by the number of cores and the two agree, give or take the processes that started and finished between samples.

The second is permission. macOS answers detailed questions about a process, its CPU time, its memory, its disk and network traffic, only to the user who owns it or to root. Activity Monitor is Apple's and reads through a system service that sees everything. A third-party monitor runs as you, so the processes owned by root or by system accounts, which is most of what sits near the top of the list, report nothing, and the app total falls short of the Mac's total.

## Making Activity Monitor's numbers agree

Sort the CPU tab by % CPU and add the top rows: on a busy Mac they pass 100% quickly. Now read the System and User figures under the list, which are shares of the whole Mac. The column is per core and the summary is per Mac, and the ratio between them is your core count.

The rest of the gap is timing. Activity Monitor samples every five seconds by default (View → Update Frequency). A process that runs for a second and exits, a shell command, a Spotlight worker, a helper an app spawned and closed, contributes to the total but never appears in the list.

## What a helper does, and why some monitors ask for one

To measure processes it does not own, a monitor needs a small privileged helper that macOS installs with your password and that answers one question: how much are these processes using? The helper runs as root, which is why a careful app keeps it optional, keeps it small, and says exactly what it reads.

Without a helper, the honest thing for a monitor to do is say so: show the system processes it cannot measure as blank, count them, and note that the list adds up to less than the total. A monitor that shows a number for kernel_task without a helper is estimating.

## Questions people ask

### Why does % CPU add up to more than 100% in Activity Monitor?

Because each core counts to 100%. An 8-core Mac can show 800% across its processes. The System, User and Idle figures under the list are shares of the whole Mac, so they always add up to 100%.

### Why do some processes show no CPU or memory in a third-party monitor?

macOS lets an app read detailed figures only for processes owned by the same user. WindowServer, kernel_task, mds_stores and other system processes belong to root or to system accounts, so they stay blank unless the monitor has a helper that macOS lets read them.

### Is a privileged helper safe?

It is a program running as root, so trust matters. A well-behaved helper is small, does nothing but read process figures, installs only when you turn it on, and can be removed from the same place. Read what the app says it does before you enable it.

## In Vitals

Vitals says how many system processes it is not measuring and that the list adds up to less than the total. Its optional helper reads those processes' figures and nothing else, and you can turn it off again in Settings → Permissions.

## Related

- [kernel_task](https://vitalsmac.com/glossary/kernel-task)
- [WindowServer](https://vitalsmac.com/glossary/windowserver)
- [% CPU](https://vitalsmac.com/glossary/cpu-percent)
- [Helper processes](https://vitalsmac.com/glossary/helper-processes)
- [mds_stores and mdworker](https://vitalsmac.com/glossary/spotlight-indexing)

Looking for something better than Activity Monitor? See [the best Activity Monitor alternatives for Mac](https://vitalsmac.com/best-activity-monitor-alternatives), or [every term in the glossary](https://vitalsmac.com/glossary).