Watts per app

Updated 23 August 2026 · the wordings quoted here are the app's own strings. Who measures this.

Every app in watts rather than in a unitless score, with its helper processes folded into one row, and the parts you cannot quit kept out of the ranking. On battery, most rows also carry what quitting would give back in minutes.

One row per app, not per process

Chrome runs as sixteen to forty processes depending on the day. Activity Monitor shows you all of them; the list here shows one row called Chrome, built by walking each process back to its application bundle. The same folding puts an iOS Simulator and every daemon it starts into a single row you can close in one action.

System daemons do not join the ranking at all. They go into one bucket labelled as system processes, because a list you can act on should not be padded with things you cannot quit. The energy still counts toward the machine's total, it just does not pretend to be a suggestion.

An app you have already quit stays on the list with the watts it spent, dimmed and marked as quit. Those watts were measured and they happened; moving them into an anonymous "system" row afterwards would quietly rewrite the last few minutes.

What the number is

The counters the app reads live on the chip, and a chip watt is not a battery watt: the pack pays roughly two and a half times more. So the figure on a row is not a raw counter reading. It is the machine's actual battery draw, minus the floor that the screen and simply being awake consume, split between apps by their share of those counters. The measurement behind that is written out separately, including why the obvious approach loses four fifths of the work on an idle Mac.

The popup and the statistics window deliberately show different averages: a short recent horizon in the popup, the whole session in the window. Numbers seen side by side will not match, and neither is wrong.

Below half a watt the row prints "less than" rather than rounding to zero. A zero would say the app spends nothing, and the row exists precisely because it spends something.

When there is no list at all

Two cases, and in both the app says so outright rather than showing an empty table.

On a machine without the counter, usually a virtual machine: "WattMate reads a per-process energy counter from the kernel, and this Mac does not have one. Every number here would be a zero, and a zero we cannot stand behind is worse than no number at all."

In the Mac App Store edition, permanently: "This edition cannot see what individual apps spend. The App Store sandbox forbids asking the system about other processes, so there is no app list and no per-app figure — not 'not yet', but never." That is why this feature exists only in the version sold from this site.

When the list is there but the minutes are not

The app list appears within seconds. The minutes take longer, and the app is explicit about the wait: "The app list is ready. Naming the minutes needs a few more samples."

Its own methodology page puts a number on that: half the time the first figure arrives within three minutes, sometimes much longer, "which is why we never promise a countdown". After the Mac wakes from sleep the wait starts over, because the measurement is built from a continuous run of windows and sleep breaks the run.

There is a second reason minutes can be missing while watts are present. Converting watts into minutes needs the machine's floor, and until that has been measured on your particular Mac the app names the app but not the gain: "Until we've measured this Mac, we can't say how much longer the charge would last."

Questions people ask

Why only three apps in the popup?

Because a menu bar panel is for a decision, not for a table. The full ranking is one click away in the statistics window, where it expands to every row.

Does it show watts while plugged in?

The list is there, but without minutes: on mains the battery is not paying for anything, so there is nothing to give back by quitting.

Why does WattMate list itself?

Because measuring costs something, and hiding our own cost while showing everyone else's would be the one row you cannot check. It is listed and not offered for quitting, since quitting the app that draws the list is not a suggestion worth making.

How often does the list update?

On the completion of a measurement window rather than every second, and only while a window is open. "Live" here means current, not animated.