All modern Mac laptops (MacBooks) feature a built-in ambient light sensor located near the webcam. By default, macOS uses this sensor to constantly monitor the lighting conditions in your room. If you walk into a dark room, macOS will automatically turn on the keyboard backlight. If the room gets brighter, it will automatically dim the keyboard to save battery.
However, this sensor can be overly sensitive. If you are sitting near a window with passing clouds, or shifting your posture so that your shadow occasionally crosses the webcam, you might notice your keyboard backlight constantly flickering up and down. This erratic dimming and brightening is highly distracting. You can disable the ambient sensor to force your keyboard backlight to stay exactly where you set it.
How to Stop Mac Keyboard Backlight Auto-Dimming
You must turn off the automatic sensor integration from the Keyboard settings.
- Click the Apple Logo in the top-left corner of your Mac’s screen.
- Select System Settings (or System Preferences on older macOS versions).
- Scroll down the left-hand navigation sidebar and click on Keyboard.
- In the main window, look for the “Keyboard brightness” section.
- Locate the toggle switch labelled Adjust keyboard brightness in low light.
- Click the toggle switch to turn it completely Off.
macOS will immediately stop polling the ambient light sensor. Your keyboard backlight will now remain static. You must use the Control Center (or the dedicated keys on your Touch Bar / function row) to manually adjust the brightness of your keys, but they will never again flicker or change on their own.