Does a Screensaver Drain Your Mac's Battery? We Measured
· Scanner Techs
Yes, a screensaver uses battery, and more than most people expect. But almost none of that is the screensaver’s own drawing. Most of it is simply the display being on. We measured it on a 14-inch MacBook Pro running on battery, and the numbers make the choice easy.
The numbers
The whole Mac’s power draw while each one was on screen, at half brightness, on battery:
| On screen | The Mac draws |
|---|---|
| Display off | 1.2 W |
| Display on, showing black | 3.3 W |
| A screensaver showing a still picture | 3.5 W |
| Flurry, from macOS | 6.1 W |
| Hello, from macOS | 7.9 W |
So a screensaver that moves costs roughly three to five watts more than a black screen, and the display being on at all costs two more on top of that. For a sense of scale, a MacBook doing light work with nothing much on screen draws a handful of watts, so a screensaver can easily double what an idle MacBook uses.
Where the power goes
The surprising part: about 3 W of an animated screensaver’s cost is macOS’s own machinery, before the screensaver draws anything interesting. We built a test screensaver that moves one small white square across a black screen, and it cost 3.0 W over plain black on its own.
That is why Flurry, Hello and every animated screensaver from anyone else land in the same few-watt band. The difference between a plain screensaver and a lavish one is small. The difference between any animated screensaver and none is not.
Does a screensaver save power, then?
No. This is a leftover belief from CRT monitors, where an unchanging image could burn into the glass and a moving picture saved the screen. A modern Mac’s display doesn’t need saving, and anything shown on it costs more power than turning it off.
What saves power is the display going to sleep. So the useful question isn’t “which screensaver” but “for how long”.
How to have both
Let the screensaver run for a few minutes, then let the display turn off. In System Settings → Lock Screen:
- Start Screen Saver when inactive: for example, after 2 minutes.
- Turn display off on battery when inactive: a few minutes later, for example after 5.
You get the screensaver when you step away briefly, and the battery when you step away for longer.
One trap: if the display is set to turn off before the screensaver starts, you’ll never see the screensaver at all. If yours never seems to come on, that’s the most likely reason. More on that here.
If you want one that’s lighter on battery
Two things make a real difference:
- A still screensaver costs almost nothing over black: 0.2 W in our test.
- A lower frame rate on battery. Drawing 30 frames a second instead of the display’s full rate saved about a watt in our tests.
Nap, our own screensaver app, does the second automatically on battery: its Paper Plane measured 6.7 W, between Flurry and Hello. The full set of measurements, including how we took them, is on our power page.
How we measured
A 14-inch MacBook Pro (M4 Pro, 2024) at 47% brightness with auto-brightness off, running on battery, with nobody touching it. Power is the whole Mac, read from the battery gauge’s own running total, averaged over two minutes after things settled. Each screensaver was compared with a black screen measured minutes earlier in the same session. Your Mac’s numbers will differ, but the order shouldn’t.
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