Is it true that Dark Mode saves battery?

The latest generations of mobile devices prioritize factors like speed and image quality, but they devour energy like crazy, and they must adopt every efficiency trick available. The so-called Dark Mode is now a central feature in popular apps and the latest versions of iOS and Android, carrying the promise of saving battery. The question is, how well does it do that job? Can Dark Mode make a difference, or has its value been exaggerated?

Almost all guides on how to optimize and save battery on mobile devices start from the same place: the screen. Depending on the specifications and user settings, the screen can consume between 30 and 50 percent of the battery. This relationship reached new extremes with the introduction of OLED screens. They look beautiful, but they are voracious with the battery.

In the case of LCD screens, the number one recommendation is to lower its brightness to the minimum tolerable for the user. Instead, if the smartphone's panel is OLED, there is another aspect to control besides brightness, and it is the use of the so-called Dark Mode. By controlling and turning off each pixel individually, an OLED screen could consume a fraction of the total energy if the content favors black and gray tones. Now, how good is Dark Mode? Is it true that it saves battery?

The Dark Mode and battery savings

The folks at PhoneBuff decided to put Dark Mode to the test on an iPhone XS Max with iOS 13. The screen brightness is identical in both cases (200 nits), the only variable is the use of Dark Mode on the left half of the screen. After simulating activity for two hours (using robots and chatbots), Dark Mode took a 5 percent advantage over the standard configuration: 88 percent battery versus 83 percent.

Two additional hours on Twitter notably widened the difference. The session with Dark Mode ended at 72 percent battery, while in normal mode it dropped to 57 percent. The pressure increased with two hours of video playback on YouTube, and here Dark Mode already has a 23 percent advantage over the normal mode (43 vs. 20). The last phase included two hours of exploring on Google Maps, however, the normal session with 20 percent battery threw in the towel after 90 minutes. At that point, the iPhone XS Max with Dark Mode activated showed 30 percent extra battery.

Of course, we must not forget that the sample size is limited, and that the evaluation only included apps with Dark Mode available. At the same time, the total savings vary depending on the overall screen brightness (there isn't much difference at 100 nits, while at 300 nits there was a 12 percent margin), but at the end of the day, the numbers in favor of Dark Mode are conclusive. Personally, I would like to see this test repeated on Samsung's flagship phones, and several comments ask the same for iPhone models with LCD.