Battery Drain Insights Energy Impact in Activity Monitor is a relative measure of how much energy an app is using right now, and lower is better. It has no unit. It is not watts, and it is not a percentage of your battery. Its use is to rank the apps on your Mac against each other, so you can see which one is busiest.
What is Energy Impact?
Apple’s definition is one line: “A relative measure of the current energy consumption of the app (lower is better)” (Apple, View energy consumption in Activity Monitor on Mac).
The word that matters is relative. The score is built so that a higher number means more energy than a lower number on the same Mac at the same time. Apple does not publish how it is worked out, and does not say what one point is worth.
What is a high Energy Impact?
Apple gives no level, so there is no official “high”. What you can rely on is the comparison inside the list.
- An app that is doing nothing shows 0.0 or close to it.
- An app that stays far above the rest of the list for more than a moment is the one working hardest.
- A score that jumps for a second and falls back is normal. Opening a window or loading a page does that.
So do not ask whether 40 is a lot. Ask whether one app is at 40 while everything else is under 2, and whether it stays there.
What does 12 hr Power mean?
It is the same score, averaged: “The average energy impact of the app in the last 12 hours, or since the Mac computer started (lower is better)”. Apple notes that this column appears only on Mac laptops.
For finding a drain, this is the better column. Energy Impact shows the moment. 12 hr Power shows who has been working all afternoon. Click the column heading to sort by it.
What do the other columns mean?
These are Apple’s descriptions, from the same page.
| Column | What it tells you |
|---|---|
| Energy Impact | The app’s energy use right now, as a relative score |
| 12 hr Power | The average of that score over the last 12 hours, or since the Mac started |
| App Nap | Whether App Nap is active for the app. macOS slows down apps you cannot see |
| Preventing Sleep | Whether the app is keeping your Mac from going to sleep |
| Graphics Card | Whether the app needs the high performance graphics card, on Macs that have more than one |
| User | The user name running the process |
Preventing Sleep deserves a look every time. An app that says Yes there keeps the Mac awake when you walk away, and can keep it awake with the lid closed.
At the bottom of the window, a Mac laptop also shows the charge that is left, the time on battery, and a graph of the battery over the last 12 hours.
Can I turn Energy Impact into a battery percentage?
No. The score has no unit and no fixed link to the charge in your battery, so no sum turns it into percent. Two Macs can show the same score for the same app and lose charge at different rates, because the screen, the battery’s age and everything else differ.
This is also why apps from the App Store do not show a true percentage per app. macOS does not hand that figure out. The article on battery usage by app has the detail, with the test we ran.
How do I use it to find what drains my battery?
- Open Activity Monitor from Applications, Utilities, and click Energy.
- Choose View, All Processes, so that programs with no window are listed too.
- Click 12 hr Power to sort. Note the top three names.
- Click Preventing Sleep to sort. Note any app that says Yes and should not.
- Come back in an hour. A name that is still at the top is your candidate.
The weak point of this method is step 5. Activity Monitor keeps nothing beyond 12 hours, and it shows background programs under names meant for engineers.
Where Battery Drain Insights fits
Battery Drain Insights does the coming back for you. It watches while your Mac is on battery, keeps the ranking for 30 days, and puts background programs first when they did more than your apps. It ranks by share of the work, measured from processor time, which is the part of energy use that software controls.
Its figure is no more a battery percentage than Energy Impact is. The difference is that it is added up over the whole time on battery and shown next to the real battery reading.
More causes, and the checks for each, are in the guide Why is my MacBook battery draining so fast?