Users of certain smartphones should definitely use Dark Mode

Not only many apps, but also smartphones often offer a dark mode. However, there is more behind the dark display than just an optical change. Dark mode also helps save battery power – at least when users use certain smartphones.

Researchers at Purdue University in Indiana, USA, have studied the effects of dark mode on smartphone battery life. As part of the study, they looked at the power consumption of six of the most commonly downloaded Android apps: Google Maps, Google News, Google Phone, Google Calendar, YouTube and Calculator. The apps were used for 60 seconds each on the Google Pixel 2, Pixel 4 and Pixel 5 devices as well as on the Motorola Moto Z3. All four smartphones have an OLED display – a crucial point in the study.

Smartphones with OLED benefit from Dark Mode

Many current mid-range and upper-range smartphones are now equipped with an OLED screen. The advantage over LCD here is the pixel-precise instead of area-wide backlighting. Since the dark mode mainly displays black or dark areas and white text, many pixels are simply turned off. This saves power in the long run. How high the energy savings turn out, however, depends on the brightness of the display, according to the researchers.

The automatic brightness, in which the smartphone regulates the luminosity of the display depending on the ambient light, mostly uses a brightness of between 30 and 40 percent indoors. Researchers at Purdue University found that an activated Dark Mode saves about 3 to 9 percent energy on average at a brightness of 30 to 50 percent. A very low value that most smartphone users will hardly notice.

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Display brightness makes the difference

However, if they use the dark mode outdoors with a display brightness of 100 percent, the savings are significantly higher. Between 39 and 47 percent battery power can be saved thanks to Dark Mode. This scenario would be conceivable for outdoor use, for example, where the high brightness is necessary due to strong sunlight.

The result is interesting because the higher display brightness should actually drain the battery faster. However, thanks to Dark Mode, the energy consumption when using the Google News app is on the same level as with 20 percent brightness. Users thus benefit twice – from the better readability of the display due to the higher brightness while saving power at the same time.

In order to perform the test as accurately as possible and to be able to observe the effects of the dark mode on the battery life separately from other smartphone functions, the researchers have developed special software. It is called Per-Frame OLED Power Profiler (PFOP).