Dark Wallpaper Battery Calculator

Estimate how much battery you'd save by switching from a bright wallpaper to a darker one. The model is deliberately simple and every assumption is shown — this is a guide, not a lab measurement.

Estimated saving

How this is calculated

• On AMOLED, display power scales roughly with the average brightness of what's on screen. A pure-white screen at full brightness draws about 1.5 W; a pure-black one draws about 0.1 W.
• The wallpaper only affects power while it's visible — on the home and lock screen. Inside apps, their own backgrounds decide the power, so that time is excluded.
• Brightness is treated as a linear multiplier on display power. Battery energy is estimated as capacity × 3.85 V.
• "Extra screen time" assumes an average whole-phone draw of about 2.5 W while the screen is on.
• On an LCD the backlight is always on, so the wallpaper makes essentially no difference — the calculator will say so.

The full reasoning, with the lab numbers behind these figures, is in Why Dark Wallpapers Save Battery on AMOLED — With Numbers. The short version: the saving is real but usually small (1–4% of a day), and brightness, dark mode and screen timeout matter more.

What this model deliberately ignores

The estimate above is a first-order one. Several real effects are left out, and all of them are small enough that including them would imply a precision the underlying numbers do not have:

• Colour, not just brightness. On an AMOLED panel the three subpixels are not equally efficient — blue is the most expensive to drive and green the least. A deep blue image therefore costs more than a green one of identical apparent brightness. The calculator treats brightness alone.
• PWM dimming. Many panels dim by flickering rather than by reducing drive current, which makes the relationship between the brightness slider and actual power draw non-linear at the low end.
• LTPO refresh switching. A panel that drops to 1 Hz on a static lock screen saves power in a way that has nothing to do with the wallpaper, and can easily exceed the wallpaper effect entirely.
• Adaptive brightness. If your phone is setting brightness automatically, ambient light dominates — walking outdoors costs more than any wallpaper choice.

The honest summary is that a dark wallpaper is a real but minor saving, worth taking if you like dark wallpapers anyway and not worth forcing if you do not. Screen timeout, brightness and dark mode in the apps you actually use are each larger levers than the image behind your icons.

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