Researchers Say Dark Mode May Help Smartphone Battery Life Less Than You Think

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Over the past few years, smartphone operating systems -- namely, Android and iOS -- have adopted Dark Mode options to reduce eye strain at night and help save battery life on devices with OLED displays. For that latter point, the general idea is that OLED-equipped smartphones don't need to power portions of the display with a black background, leading to power savings.

However, researchers at Perdue University decided to question that perception about how much Dark Mode improves efficiency. "When the industry rushed to adopt dark mode, it didn't have the tools yet to accurately measure power draw by the pixels," said Purdue Electrical and Computer Engineering Professor Charlie Hu.

To test this theory, the researchers used a sample of four Android smartphones: the Google Pixel 2, Pixel 4, Pixel 5, and Motorola Moto Z3. With these phones, they tested power consumption with Google Maps, Google News, Google Calendar, YouTube, and Calculator -- all apps that can leverage Dark Mode. Each app was tested for 60 seconds to see how they performed versus using the same app in its standard, more white-skewed appearance.

Following their extensive testing regimen, the researchers discovered that Dark Mode resulted in an average power savings of only 3 percent to 9 percent on the collection of smartphones. On the high end, 9 percent is nothing to scoff at, but the researchers expected more significant power savings.

However, there are specific scenarios where users could see a much greater benefit from switching to Dark Mode, i.e., when using a phone outside with the brightness cranked up to 100 percent. "Switching from light mode to dark mode at 100% brightness saves an average of 39%-47% battery power," Perdue University writes. "So, turning on dark mode while your phone's screen is that bright could allow your phone to last a lot longer than if you had stayed in light mode."

According to Hu and his research team, previous tests of power draw from Dark Mode took into account all hardware within a smartphone, including its power-hungry SoC and other components (i.e., WiFi, Bluetooth, 4G LTE modem, etc.), which made them inaccurate. Our tool can accurately isolate the portion of battery drain by the OLED display," said Purdue Ph.D. student Pranab Dash.

For those that prefer to use Dark Mode to help reduce eye strain, it's pretty much a wash compared to the standard display mode, according to the researchers. "Using the Google News app in light mode at 20% brightness on the Pixel 5, for example, draws the same amount of power as when the phone is at 50% brightness in dark mode," the team explains.

"So, if looking at your phone in dark mode is easier on your eyes, but you need the higher brightness to see better, you don't have to worry about this brightness level taking more of a toll on your phone's battery life."

Although Hu and his team only tested using Android, the findings would similarly apply to Apple iPhones equipped with an OLED display (i.e., the iPhone 12 family).