Android: Turn Off Adaptive Brightness (Auto-Brightness) Manually

Adaptive brightness uses the light sensor near the front camera to measure the light around you and adjusts the screen automatically. It also learns from manual adjustments you make in certain lighting conditions, so the brightness level it picks can shift over time even without you touching the slider.

This is useful outdoors in bright sunlight or in a dark room at night, where manual brightness rarely keeps up. It becomes a problem when you want a stable, predictable brightness, when the sensor reacts to shadows or reflections, or when the screen dims too aggressively for reading.

To turn it off or back on:

Tap on Settings ➔ Tap on Display ➔ Enable or disable Adaptive brightness

With the toggle off, the brightness slider stays exactly where you set it until you change it again. Keep in mind that disabling it can increase battery use in bright environments, since the screen no longer lowers itself automatically when it is not needed.