Our friends at XDA Developers did a little experiment and figured out that you can save about 6 percent battery life per hour at 20 percent brightness by using a black wallpaper on an AMOLED display, and about 8 percent per hour at full brightness.

Does using AMOLED wallpaper save battery?

When the pixel is black, it isn't producing any light. When the pixel is white, it's producing light. In other words, if you use a black background on an AMOLED display, your display will produce less light. This will help save battery power, squeezing more battery life out of your device.

What wallpaper uses less battery?

If your smartphone boasts an AMOLED display, then applying black coloured wallpapers will help you save battery life. This is because pixels that make the AMOLED displays only utilize battery power to illuminate light colours and don't need any energy to show black colour.