Which display drains more battery, AMOLED or LCD?

You can buy a laptop with an OLED screen now, but should you?

There's been a test done with the same device and the results were that AMOLED drains 10-25 percent more battery than IPS LCD, particularly during tests where brighter pixels were displayed. On an AMOLED screen, each tiny pixels are lit and that causes battery drain, however, when displaying black pixels, they don't light up therefore saving battery. However, overall it still drains more battery than LCD. People assume AMOLED saves more battery because the pixels don't light up when black is being displayed, however that's a misconception and not entirely true based on their beliefs. The AMOLED panel itself demands more power to light up bright pixels, however it won't matter to the average person because each hardware is unique and it depends on a variety of factors when you're considering battery life, factors such as battery size, CPU chip type, operating system efficiency, etc.

This video explains the technology in depth:

At 5:45 :

"... As brightness of the display increases , its depiction of white becomes less accurate... White backgrounds consume significantly more power in AMOLED displays than IPS ones since all sub pixels must be set to max brightness whereas IPS lighting provides consistent lighting from the backlight underneath so often manufacturers will often limit the brightness of some sub pixels in these AMOLED displays to conserve battery life..."

In the general case, LCD takes considerably more power.

1. The LCD has a single, unified white light source that illuminates the entire back of the panel.
2. A polarization film absorbs all light that isn’t polarized: 50% of the light is absorbed.
3. Transparent conductors like indium tin oxide and thin film transistors are printed onto a layer of glass that controls each of the pixels: this absorbs around 20% of the light.
4. Liquid crystal pixel cells are trapped on top of each transistor. Even when the polarization is aligned (the pixel is “on”), these waste about 50% of the light.
5. When the liquid crystal cell is “off”, these block nearly all of the light - to produce black. For a medium-intensity image, the overall typical waste is, of course, 50%.
6. A Bayer filter colors each of the pixels as red, green or blue, throwing away the other 2/3 of the colors: 66% of the white is wasted this way.

AMOLED screens are considerably simpler. They carry some minor problems, mostly because there are fewer vendors who know how to build them with the needed uniformity and reliability.

1. Thin film transistors and transparent conductors are not necessary, since they can be put on the back of the substrate: no light needs to shine through them.
2. Organic LED materials are printed on top of the transistor layer, essentially producing lots of tiny LEDs of different colors.
3. The tiny LEDs themselves, as well as the mechanism for powering them, is far less efficient than the large, single-power-source white LEDs of an LCD, perhaps by about 50%. This is pretty much the only relative waste in an AMOLED display.
4. A “black” pixel has no light behind it, so it takes no power. A green pixel only emits green; there is no white light to block, so it’s not wasting the other 66%.
5. AMOLED displays, not including the glass, are around 0.75mm thick, compared to about 2.5mm for an LCD. This leaves room for more battery.

I would have to say that a LCD (with no backlight) uses less power than a AMOLED.

Amoeld need to have some sore of lighting on for it to be readable. that takes power.

A monochrome LCD, without the backlight, can operate on as little as 2.7V (although it is best to stay above 3.3V). The colder the environment, the more voltage required.

A monochrome can turn on and is readable in the daylight with as little as 1mA to 3mA of current (the larger the display the more power needed, the colder the temperature, the more power needed)

Segment displays like in a digital watch, with no backlight, will run for years on small watch batteries.

So I would say a monochrome, Liquid Crystal Display uses less power than a amoled.

Here is an article dealing with low power displays for battery powered and solar powered products.

I am a design engineer at Focus Displays, the link is to show supporting current draw.

<Battery and solar-powered low voltage LCD Displays>

All other specs kept same, definitely the LCD as its backlighting panel will be using up energy. For the same perceived brightness, AMOLED displays will use up equal or lesser energy - especially when the content to be displayed has lot of blacks, the latter can turn off the individual LEDs and save energy.