Does dark mode really save your smartphone battery?
Is dark mode just a trendy addition, or does it really help save battery life? Smartphone users are increasingly switching to a dark background, hoping for longer device operation. Does it actually affect energy consumption, or is it just a myth? Discover how dark mode works and in which circumstances it can extend battery life.
The screen is an integral part of smartphones but also one of the biggest energy consumers. Although manufacturers often highlight that the device can operate in standby mode for many weeks, actively displaying content significantly shortens this time, often to just a few hours.
So, how can you reduce battery consumption? The simplest way would be to avoid turning on the screen; however, we buy a smartphone to use it, after all.
By analysing what the display shows, you can draw interesting conclusions. On the screenshot, key elements such as graphics, texts, and icons occupy less than 30% of the screen's surface. The rest is primarily a white background.
This background largely serves a visual function, meaning up to 70% of the screen lights up to make other elements visible. Wouldn't it be better if this background didn't require energy?
It turns out that managing the screen surface can be more efficient. In the case of LCD screens, they are uniformly backlit, regardless of the colours displayed. However, OLED displays function differently, using organic diodes that allow each pixel to operate independently. The brightness of each pixel can be adjusted separately.
OLED panels are noted not only for image quality but also for energy efficiency. Pixels responsible for deep black are not activated at all, meaning they don't consume energy.
Remember the mentioned 70% of the screen's surface that lights up unnecessarily? If you changed the colours and switched the white background to black, only the displayed elements on the OLED screen would consume energy, occupying less than one-third of the screen's surface.
Dark mode and smartphone battery savings
In an experiment, a smartphone with a 4.5-inch OLED screen and a 4500 mAh battery was used to create two different sets of screenshots of a website. The first had a white background:
the second a black background:
Each set was turned into a slideshow, which was displayed until the battery was exhausted.
The tests started with a fully charged battery at 100%. During the experiment, the smartphone operated in airplane mode, with no additional applications, and at maximum brightness, so any differences in energy consumption were due only to the colour of the background.
The smartphone ran out of power:
- in light mode after 10 hours and 25 minutes;
- in dark mode after 13 hours and 31 minutes.
The results are clear. Enabling dark mode allowed the smartphone to operate for 3 hours and 6 minutes longer, which constitutes a 29% increase in operating time.
Let me remind you that both times the display was showing the same text and identical graphics. The difference in performance was solely due to the background colour.
How does dark mode impact the environment?
Longer battery life means less frequent charging. Fewer charges mean energy savings, which reduces emissions associated with coal usage.
It is predicted that up to 75% of new smartphones entering the market will have an OLED screen.
On computers, the energy-saving advantages of dark mode are smaller due to less frequent use of OLED technology, but they are not insignificant. Dark backgrounds are less straining on the eyes, which is beneficial when working in low light at night.
As a result, dark mode can lead to significant energy savings if widely adopted by smartphone users.
