One app, kept in sight

Updated 6 November 2026 · Who measures this.

Star one app, and WattMate keeps it in the menu bar with its watts. Click it and it answers "is this normal?" with a verdict on the last hour, and it tells you when the app stops being normal. Most people have one app they keep an eye on: the one they are building, the one that surprised them last week, the one that is not supposed to be doing anything right now.

What it looks like

A star on the app's row in the list, or on its page. From then on the app sits first in the list whatever it uses, and gets its own item in the menu bar: its icon and its watts, the same figure the row prints, rounded the same way. When the app is closed the item dims and shows a dash rather than a stale number. The item is a switch in Settings ("Show the favorite app in the menu bar"), and it can be dragged out of the menu bar like any other.

Since version 1.5 the star can also go on an AI coding agent. Its item then shows the watts of the task the agent is running, and only the agent's symbol, without a number, while it is idle. Its panel says what the agent is doing and what its tasks cost instead of the hour described below, and the notification below does not watch it.

Click the item and a panel opens. Its first line is a verdict about the last hour, the second is the reason, and under them the hour itself: 40 bars, one for each measurement window of a minute or two, with the app's usual level drawn across them as a dashed line. "Usual" is the median of that hour, not the average, so a 20-minute spike does not move it much.

The verdict

There are 9 outcomes, and the order matters: the app checks the loud ones first. 8 are here; the ninth, a phone charging from the Mac, has a section of its own below.

"Above its usual" needs a clear margin over the median, held for several bars in a row. 1 bar over is a spike, 2 are a coincidence; the verdict does not go orange on either. A "new peak" is named when the hour's highest bar is recent, because that is an event; an hour-old peak is a fact and sits under the ribbon instead.

The notification

In Settings, on the Notifications tab, in the Apps group: "Favorite goes over its limit", with 2 numbers, "Above" so many watts and "For longer than" so many minutes. By default, 10 watts for 5 minutes. The rule is the same one the panel prints: every window in the trailing run must be above the line, the run must cover the whole threshold, and the newest window must be fresh. A run interrupted by sleep or a cable starts over.

The notification reads "Xcode is using 13.5 W", then "Above 10 W for 7 min now. Open the panel to see what it has been doing." It comes once per spell: the app has to fall back under the line before it can ring again. It never comes on power, because on power the number it would quote is not a measurement of the battery.

What it says when it cannot say

While a phone charges from the Mac, the item shows a dash and the panel says why: "the cable hides what apps use · the last hour ends where the cable began". The phone's current sits inside the machine's draw and leaves no trace on the chip, so any per-app figure in that hour would be inflated by it. The ribbon stops where the cable began, and if the whole hour went that way the panel says so: "the last hour was spent with a phone on the cable".

On power the panel does not judge. It still draws the hour up to the cable, and it still says "usually" from the battery windows it has, but the watts of the moment come from a different instrument, and comparing one against the other would call an app "above its usual" at the exact moment you plugged in.

Questions people ask

Why a verdict and not a chart?

Because a chart makes you do the judging, and a menu bar number only tells you something is growing, not why. The panel answers the first half, whether it is growing beyond its usual, and hands the second half to the app's page and to Instruments.

How long before it knows what is usual?

A few bars, several minutes on battery. Until then the verdict says "Still measuring", and no time is promised, because the warm-up length is a median, not a guarantee. The threshold notification does not wait for that: it has a line of its own.

Does the item drain anything itself?

The item reads the same list the main panel keeps, rebuilt each time a window completes, and on power it keeps that list alive, polling less often than the open main panel does. Its own cost has not been measured separately yet, so this page does not put a number on it.

How it was checked

What this doesn't show

• More than one app. 2 stars would mean 2 items in the menu bar and 2 panels, and the feature would turn into the list it was meant to spare you from. Starring a second app moves the star.
• Anything measured on power. Windows are written while the Mac runs off the battery, because that is where power use can be measured. On power the ribbon shows what was recorded before the cable, and nothing after it.
• Why an app is growing. The panel says whether it is beyond its usual. The why is for the app's page and for Instruments.

Related: watts per app · the quit receipt · what each app actually costs · how we count