Screen brightness needs to suit the light around you. Auto-Brightness adjusts your iPhone or iPad display automatically as that light changes. It uses the built-in ambient light sensor to dim the screen in dark places and brighten it in stronger light.
Auto-Brightness is on by default. Leaving it enabled can reduce the unnecessary power use of a screen that stays too bright in dim surroundings. Apple warns that turning it off may increase power consumption.
Turning off Auto-Brightness stops its adjustment to ambient light, but it does not stop every kind of screen dimming. A device that gets too warm may still dim its display until it cools down.
For an immediate adjustment, the brightness slider is available in Control Center or Settings > Display & Brightness.
Steps to configure automatic screen brightness on iPhone and iPad:
- Open the Settings app on your iPhone or iPad.
- Tap Accessibility.
On iOS 27 and iPadOS 27, Auto-Brightness remains under Accessibility. The Automatic switch under Appearance schedules Light and Dark Mode instead. Other Settings entries around these rows can vary by device.
- Tap Display & Text Size.
- Scroll to Auto-Brightness near the bottom of the screen.
- Turn Auto-Brightness on or off.
A green switch means on and adjusts the screen to the surrounding light; a gray switch means off and leaves brightness adjustment to you. With Auto-Brightness on, Apple describes the brightness slider moving as the surrounding light changes.