Dark mode might not be a silver bullet for improved battery life

Dark mode is touted as one of the better features on phones today that allows devices with OLED screens to save power compared to a typical light mode. This is because OLED displays can turn off individual pixels to display black colors, which saves juice.

However, a new study by researchers at Purdue University has shown that switching to dark mode may not make much of a difference in power consumption with typical usage.

The researchers examined six apps – namely Calculator, Google Calendar, Google Maps, Google News, Google Phone and YouTube – with the newly developed tool called Per-Frame OLED Power Profiler (PFOP). The team then looked at how dark mode for each app on the Pixel 2, Pixel 4, Pixel 5, and Moto Z3 affected one minute of activity.

Related: Do you love dark mode? Here’s why you want to avoid it

The result? Well, the team found that many consumers use automatic brightness settings that keep indoor brightness at around “30-40%”. However, the researchers said that switching from light mode at 30-50% brightness to dark mode on all devices tested only saved between 3 and 9 percent power on average.

However, the study found that users would get more significant energy savings if they switched from a bright, high-brightness mode to the dark mode. In fact, it has been found that switching from a bright mode with 100% brightness (as you might expect outdoors in the sun) to dark mode could save 39 to 47% juice. This is a huge win and could add up to more than just a few extra minutes of extra performance.

The study also claimed that Android’s battery usage feature doesn’t take dark mode into account when calculating an app’s power consumption. The team says they developed a tool called Android Battery + that takes dark mode into account. Purdue researchers plan to release the PFOP tool as open source and include the Android Battery + feature in the Android Open Source Project. The Battery + functionality is highlighted in the red box in the image below.

However, some of these results seem like a no-brainer, as we already know that drastically high brightness in light mode can chew through a phone’s battery. So it is obvious that switching from a bright mode in super-duper high brightness to a dark mode will see greater gains than switching from a light mode in moderate brightness. Google even illustrated the connection between dark mode and brightness in 2018 with its own research.

What is interesting, however, is how little dark mode can do if you prefer low to medium brightness anyway. As a result, those who don’t turn up the brightness of their phone in the first place may not want to switch to dark mode if they hope for big energy gains.

We’d also be happy to have this test done with the same brightness measurement for each device (based on nits), as some phones have brighter screens than others. As a result, the 100% brightness on one phone may not be as bright as the 100% brightness on another.