Dark mode is often recommended as a way to save battery on devices like smartphones, tablets, and laptops. But can it really boost your mobile device’s battery backup? Here’s everything you need to know.
What is Dark Mode?
Before talking about the impact of dark mode on the battery life of your device, it is good to understand it.
Dark mode, also known as dark theme, is a display setting on many devices that changes the background color of the system and its apps from a light color to black or dark gray and makes the text in a light color, usually white.
It potentially has several benefits, including reducing power consumption and extending the battery life of your device. However, it’s not as simple as activating dark mode and waiting for the battery life to increase by a few hours.
The impact of dark mode on a device’s battery life depends on two key factors: the screen technology used in your device and the system background color when dark mode is enabled. So let’s start with screen technology.
Screen technologies and dark mode
Virtually all modern mobile devices with a screen use one of the two main display technologies: OLED and LCD.
OLED or Organic Light Emitting Diode displays have self-emitting pixels, which means that the pixels in an OLED display can produce their own light when an electric current passes through them. They therefore do not need a backlight to create images and text. It also means that when an OLED screen needs to output the color black, it simply turns off the pixels in the required part of the screen and you get a completely black color.
So when you enable dark mode on a device with an OLED screen, whether it’s a phone, tablet, or laptop, the device needs to power a relatively lower number of pixels whenever the background or parts of it are entirely black. Therefore, it consumes less power and your device battery lasts longer. However, the impact on battery life will depend on how often parts of your device’s screen are completely black.
On the other hand, LCD or liquid crystal displays need a backlight, usually LEDs or mini-LEDs, to illuminate the pixels to produce images and texts. So when an LCD needs to create a black color, it tries to block the backlight in areas of the screen where black is needed. However, even when it displays black color, the LEDs are still on and the display battery is unable to completely block the light. As a result, some light leaks out and the blacks of most LCD screens appear gray.
However, LCDs have come a long way in the last few years and now we have technologies like local dimming and mini-LED. Both offer better backlight control, which results in significantly better black levels. Thus, a display using LCD technology with Mini-LED backlighting and full local dimming (FALD) may turn off some of the LEDs when it needs to display the black color.
So using dark mode on devices with an LCD screen may also result in some power savings, as there is support for full local dimming and Mini-LED backlighting, because the screen will not use all the LEDs when the background is black. That said, local dimming and Mini-LED backlighting are relatively rare on mobile devices. You’ll only find these technologies in certain laptops and iPad Pro models. And the energy savings will depend on the number of dimming zones, the local dimming algorithm and the size of a zone.
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Background color is important
Besides screen technology, the background color a platform or app uses when dark mode is enabled can dictate whether you’ll see a benefit on the battery front. As mentioned, all OLED devices can turn off pixels, and some LCD devices can dim part of their backlight to display the color black. This saves power and extends the battery life of a device.
However, this is only possible when the background elements are actually black and not a shade of gray. But unfortunately, many platforms, devices, and services use a dark gray background, instead of black, for aesthetic reasons. So the extent of battery life savings with dark mode may vary.
How much energy savings can you expect with dark mode?
The amount of power savings you can expect from using dark mode depends a lot on how bright your device is. This is because the higher the brightness level of your phone or laptop, the faster its battery will drain.
According to a Purdue University 2021 Study, if you keep your OLED phone brightness level around 30%-50%, you can only expect about 3%-9% power savings. However, if your phone is still at 100% brightness, dark mode will save you around 39% to 47% of your battery. You’ll likely get similar results on OLED tablets and laptops.
LCD devices with FALD and Mini-LED backlights are likely to see worse power savings than OLED devices because their backlight control is not at the pixel level. So they will be less likely to dim the LEDs and save energy.
Better battery life but with caveats
Overall, dark mode can extend battery life. But there are plenty of caveats. It’s especially useful for people who have a phone, tablet, or laptop with an OLED screen. But even then, your device’s platforms and apps should have a dark mode black background, not a gray version. Otherwise, you won’t see any benefit even with an OLED display. LCD users are generally out of luck unless you have a mobile device that uses local dimming and Mini-LED backlighting, which is rare. And finally, let’s not forget the brightness of the device.
If you’re concerned about your smartphone’s battery health, check out our list of ways you could be ruining your battery.
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