Black wallpaper on an AMOLED display: how much battery does it save?



A few weeks ago, we posted a selection of wallpapers ideal for AMOLED displays. The images in question had one thing in common – they were predominantly black – and that's not only because of the striking contrast achieved by screens of that type. It is a known fact that on AMOLED screens, pixels that are totally black draw no power at all. That is why putting a solid black wallpaper on such a display results in lower power consumption, thus improved device battery life. But at the end of the day, how much power would this save? Surprisingly, not as much as you'd expect.

The experiment


To test how much battery life I could gain by switching to a black wallpaper, I gathered three phones with AMOLED displays that I had access to – the Samsung Galaxy S7 edge, the OnePlus 3, and the Nexus 6P. Then I set their screen brightness to a constant level – 200 nits when displaying a white image. Normally, a smartphone screen's brightness fluctuates below and above that point (if auto brightness is enabled, of course), but 200 nits is a reasonable average. Finally, I ensured that no background apps were interfering with my experiment.

My testing consisted of setting a series of 50 images as wallpapers and measuring what effect that had on power consumption. The average value of all 50 measurements served to show how much power each phone would draw with a typical wallpaper. Then I compared the figure against having a solid black image set as a wallpaper. I made a test using a solid white image as well, just to see what each phone's consumption would be in a worst-case scenario. Here's a chart with the results:


Now it is time to make sense of all that data, and I'll try to do that as plainly and simply as possible. Using the figures above, I can calculate how much each phone's power consumption drops if I switch to a pure black wallpaper. If I divide the result by the phone's battery capacity, I'll know how much battery I'd be saving. Okay, I'll stop with the mumbo jumbo now and give you some actual numbers:

  • On the Galaxy S7 edge: savings of about 1.2% battery charge per hour spent on the home/lock screen or 3.2% at best (if you switch from a completely white to a solid black wallpaper).
  • On the OnePlus 3: savings of about 0.6% battery charge per hour spent on the home/lock screen or 4.5% at best.
  • On the Nexus 6P: savings of about 1.4% battery charge per hour spent on the home/lock screen or 4.6% at best.

Not a lot, huh? 

Conclusion


The power-saving potential of AMOLED displays is undeniable. It is one of the reasons why some power users go the extra mile and apply dark or black user interface themes to the AMOLED screens of their devices. It is why geeky phones like the OnePlus 3 have that option built right into their UIs. And it is also why some smartwatches use black extensively throughout their menus to compensate for their tiny batteries.

But as our data shows, simply changing your phone's wallpaper to a black image doesn't have that much of an effect on battery life. Yes, you will gain a few more minutes of screen-on time. Perhaps you'll gain more if your device has a smaller than average battery or if you keep your screen set on high brightness all the time. But on a typical high-end handset packing an AMOLED display, the difference would be small, if noticeable at all. That's not only because the power savings are underwhelming, as we measured, but also because most of the time we spend with our phones is spent within an app or a game. 

So, are you surprised by the results? Have you experienced savings greater than what we measured? Or do you have any battery-saving tips to share? The comment section below is all yours!

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29 Comments

1. sissy246

Posts: 7035; Member since: Mar 04, 2015

I have a full screen photo for my home screen but I like my settings in white.

28. zeeBomb

Posts: 2318; Member since: Aug 14, 2014

PA should do more articles like these... they're great. Even tho Android pit conducted a testike this already

2. Herro

Posts: 4; Member since: Sep 19, 2016

Not surprised at all. I would like to see some kind of test that shows energy usage on AMOLED vs LCD when viewing white. That would more accurately reflect real world usage since most people are viewing black text on a white background most of the time.

6. Macready

Posts: 1813; Member since: Dec 08, 2014

No, we usually look at mixed content, because even a website like this one, is partially white and this is probably the most white that I see during my browsing. And taking into account mixed content is what a good battery tool already does when measuring average consumption.

13. SYSTEM_LORD

Posts: 1168; Member since: Oct 05, 2015

I beg to differ. The one color we view most is white. To say that you view any given color more than white is dishonest. With that being said, a picture that has maybe 1/3 white and the rest various shades would better approximate. When I'm registering for classes, reading syllabi and documents, going through sites, reading articles, doing Google searches, or even social media, it's mainly white or some shade thereof. Anandtech has already done some extensive tests regarding the power draw of different screen technologies. They believe that AMOLED panels have the potential to surpass LCD with power consumption, but the best LCD screen has lower overall power draw than the best AMOLED screens.

20. Macready

Posts: 1813; Member since: Dec 08, 2014

If you read my post correctly, I didn't suggest any other color than white is seen more. The whole "dishonest" comment is built on air, not what I actually wrote. My point was that there's little sense in comparing white pages with text for a test as suggested by the poster before me, because we usually look at mixed content, even if a large chunk of that content contains white. For AMOLED, that makes a big difference in practice. Leave your AMOLED screen on a fully white page with text at 200 nits vs the average mixed content can easily make a factor 2 or 3 difference in effieciency. Even if white is still the most seen "color". I know, because I use both LCD and AMOLED screens for the same purposes. And for my use, the AMOLED screen wins. Not for browsing, where it narrowly loses out, but because I do more than browsing: view and edit pictures, view movies, and browse through menus.

3. KingSam

Posts: 1401; Member since: Mar 13, 2016

Not surprised considering nobody has their phone on the home screen for extended periods. The whole UI in dark mode would make sense. But the contrast of the wallpapers make them cook.

11. RebelwithoutaClue unregistered

I think he didn't even open apps, just show the home screen with the wallpaper. So real life difference would be even less.

4. kamejoko

Posts: 248; Member since: Nov 10, 2011

Yes! this not only display eat battery. Include all system. Must check only power eat on display.

7. Macready

Posts: 1813; Member since: Dec 08, 2014

what?

9. trojan_horse

Posts: 5868; Member since: May 06, 2016

Maybe it's: "must check only power draw on display". I still do not get the meaning of post #4. haha

5. sachouba

Posts: 264; Member since: Jun 08, 2014

QHD is useless, OnePlus sticks to 1080p to save power. ...Wait, what ?

8. Macready

Posts: 1813; Member since: Dec 08, 2014

Yes, it's a myth repeated over and over and one that is used against the future advent of 4K displays (for VR) too. Of course, extra GPU/CPU power during rendering does consume more energy WHEN/IF you decide to render at a higher resolution. But just static display consumption is usually no worse in practice, because the fill factor is kept the same (or even better). This was already explained by Samsung years ago.

12. RebelwithoutaClue unregistered

One would think with Amoled, where each pixel is either on or off, more pixels would consume more power.

21. Macready

Posts: 1813; Member since: Dec 08, 2014

Pixels aren't just on or off, brightness varies too. But for the same surface, a larger resolution display obviously will use more pixels to paint the same object, but those pixels are smaller and each of them draws less power than the larger pixels, for a similar total amount of power. In some cases even less power.

14. SYSTEM_LORD

Posts: 1168; Member since: Oct 05, 2015

Right. The only time the resolution is an issue is when you do intensive GPU related tasks. At those times you want a GPU that's operating at only part of its maximum capabilities, as thus is the best way to operate anything (including the human body).

10. tedkord

Posts: 17198; Member since: Jun 17, 2009

I have mine set with a black theme and dark wallpapers just because I like the look. Never cared for bright white screens.

15. 10ATP

Posts: 3; Member since: Oct 18, 2016

Any power saved no matter how little, helps. Especially when it comes to something of little use as on the home screen. I have been using a black home screen wallpaper for 5 years.

26. tacarat

Posts: 854; Member since: Apr 22, 2013

Yep. Full power tweaking is about lots of small wins and hopefully a few big ones.

16. Nine1Sickness

Posts: 896; Member since: Jan 30, 2011

If you have a high end gaming PC, dimming the monitor will not save you much on your electricity bill.

17. Pabliell

Posts: 179; Member since: Mar 22, 2016

People complain that most of the web pages have white background. I don't have that problem since I changed my browser to a browser with themes - UC Browser. All web pages have black background with white or gray font. It's not the fastest browser out there, but it's fast enough for a daily driver. This comment was not sponsored, I simply love additional half an hour of screen on time.

18. HomerS

Posts: 419; Member since: Sep 19, 2014

Phonarena are you sure about the decimal, don't you mean 12% and 32% on the S7, 6% and 45% on the Oneplus 3, 14% and 46% on the Nexus P?

22. Tuxedo

Posts: 356; Member since: Mar 19, 2013

I don't know what kind of math you did there but using S7E numbers: White: 1078 mW Black: 615 mW 1078/615 = 1.75 or 175% or an additional 75% in battery life.

24. Pabliell

Posts: 179; Member since: Mar 22, 2016

Everything is fine. They said using a white background uses X% more of battery charge per hour. Which means exactly what you said.

23. chocowii

Posts: 478; Member since: Jan 30, 2014

Results are insignificant.

25. othmanusse

Posts: 9; Member since: Jul 29, 2015

please make a comparison if we put FHD or QHD resolution in galaxy S7 edge with android N

27. steelew

Posts: 219; Member since: Jun 04, 2012

So if you are using The brightness slider, where is 200 nits on the 6P? I keep mine at 98% brightness most of the time and I use black themes (more for the look and to not kill my eyes). Thanks. White is mostly for using my phone as a flashlight.

29. epdm2be

Posts: 818; Member since: Apr 20, 2012

"...doesn't have that much of an effect on battery life..." Who ever wrote this article (as there isn't an editor mentioned), your calculations are wrong! From your table I calculated the following . With regards to the S7 edge which has a 13860 mWh battery I get the following figures (see below) .The source o/t battery info is from iFixit which clearly shows 3,85v X 3600mA and 13,86W (see:https://nl.ifixit.com/Teardown/Samsung+Galaxy+S7+Edge+Teardown/56845) 13860/1078= 12,85 hours total potential screen on time (white screen) 13860/615= 22.53 hours total potential screen on time (black screen) +75% 13860/788= 17.59 hours total potential screen on time (average screen) +37% So essence if Google engineers would have used more black in their UI instead of white savings could have been an additional +30% on average! And you dare to dismiss this as insignificant? Are you insane! Figures from other devices are similar. IMHO we must URGE Google to use more black in future (and present) versions of Android. And articles like these which dismisses the significance of using black on AMOLed screened devices should be dome properly and honestly. Or can I suspect PA's opinion to change by the time Apple uses AMOLed screens in their devices? Some tips to preserve battery-power. Kill the Mediaserver-service whenever it roars its battery-wasting prowess (with a special apk) or by stopping Media-storage manually when it eats away battery. Disable the google apps that you don't need (particularly the ones that invoke the mediaserver-bug) USE a black lockscreen. Contrary to what this article says BLACK does SIGNIFICANTLY save on battery. If possible, use themes that create BLACK notification panels, black settings screens and use black backgrounds when possible. Like dialer, calculator etc... obviously this only works on AMOled equipped devices. Don't use too many widgets. Keep syncing and email-fetching to a minimum during the (work-)day. use inverted colours when webpages use too much white or use dark alternatives like bgoogle.com instead of google.com Just a handfull tips, I hope they are usefull to (amoled) users

30. w1000i

Posts: 238; Member since: Jul 22, 2015

I'd like to see another test for playing video ( bright video vs dark video) and the effect on battery

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