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.

Display type

Screen-on time per day: 5 hours

Time spent on the home / lock screen: 20% of screen-on time

Average screen brightness: 60%

How dark is your wallpaper? Medium

0 = near-black · 100 = bright / white. Compared against a typical bright wallpaper (≈85%).

Battery capacity: 4500 mAh

Estimated saving

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of a full charge, per day

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energy saved per day

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extra screen time per day

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over a full year

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.

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