Do dark wallpapers really save battery on OLED screens?

You may have heard that a dark wallpaper makes your phone's battery last longer. It is true, but only on certain screens, and the real-world gain is smaller than the headlines suggest. Here is how it actually works.

Two kinds of screen

Most screens today are either LCD or OLED. An LCD panel uses a backlight that shines through a layer of liquid crystals and colour filters. The backlight is on whenever the screen is on, so a black pixel is simply a pixel that blocks the light. It still costs energy.

An OLED panel has no backlight. Each pixel produces its own light, and a black pixel is a pixel that is switched off. That is why OLED screens show such deep blacks, and why black areas use almost no power.

Most recent flagship and mid-range phones use OLED (often branded AMOLED or Super Retina), as do many newer laptops and TVs. Many budget phones, most desktop monitors and older laptops still use LCD.

How much does a dark wallpaper save?

On an OLED screen, power use rises with how bright and how white the picture is. A mostly dark image at high brightness can use noticeably less power than a bright one. Independent tests of dark mode on OLED phones have found meaningful savings at full brightness, and much smaller ones at the moderate brightness most people use indoors.

Your wallpaper is also only visible part of the time, on the home screen and lock screen, behind your icons. Once you open an app, the app fills the screen. So switching to a dark wallpaper alone gives a small but real benefit. Combined with dark mode in your apps, the effect is much larger.

True black versus “almost black”

OLED pixels only switch off when they show pure black. A very dark grey still lights the pixel faintly. Space photographs, night skies and the black backgrounds of many nebula images are ideal, because large parts of the frame are genuinely black. Dark forest or ocean scenes help less, because they are mostly deep greens and blues rather than black.

What about burn-in?

OLED screens can slowly retain a faint ghost of elements that stay in the same place for very long periods, such as status bars or navigation buttons. Your wallpaper is rarely the cause, since icons and widgets sit on top of it and you change it occasionally. Modern phones also shift pixels slightly and dim static elements to reduce the risk. If you are concerned, change your wallpaper now and then and avoid extremely high-contrast static designs at maximum brightness.

The short version

• LCD screen: a dark wallpaper makes no difference to battery life.
• OLED screen: a dark wallpaper saves a little, most of all at high brightness and when the image contains true black.
• Bigger savings come from dark mode in apps, lower brightness and shorter screen time-outs.

If you want the benefit, browse our black wallpapers or the Space & Earth collection, where deep space backgrounds give OLED screens plenty of switched-off pixels.