Glossary
Energy impact
A relative measure of how much energy an app is using right now. Lower is better.
What it is
Apple describes energy impact as a relative measure of an app's current energy consumption. It combines CPU time with things like how often the app wakes the processor, GPU use, and disk and network activity.
It has no unit. It is useful for comparing apps with each other, not as a wattage.
Why it matters
On a laptop, energy impact tells you which app is costing you battery. An app with modest CPU can still have high energy impact if it wakes the Mac constantly.
In Activity Monitor
The Energy tab: Energy Impact now, and 12 hr Power, the average over the last 12 hours or since the Mac started.
In iKnowMyMac
The Battery tab lists apps sorted by energy, the Overview shows power by app, and Sleep & Battery shows overnight drain by app.
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