Modern MacBooks are equipped with built-in ambient light sensors that continuously monitor the brightness of your surrounding environment and automatically adjust your screen’s brightness to match. While this feature is genuinely useful in many situations — it brightens the display in sunny outdoor environments and dims it in dark rooms — it can be genuinely frustrating in others. If you are editing photos and need a consistent, predictable display, or if the screen keeps pulsing brighter and dimmer while you watch a movie, manually taking control of your screen brightness makes sense.
How to Turn Off Auto-Brightness on macOS Ventura, Sonoma, and Later
Apple moved the display settings into the redesigned System Settings app in macOS Ventura. Follow these steps if your Mac is running Ventura (13) or any newer version:
- Click the Apple menu () in the top-left corner of your screen.
- Select System Settings.
- In the left-hand sidebar, scroll down and click on Displays.
- Look for the setting labelled Automatically adjust brightness on the right side of the window.
- Click the toggle switch next to it to turn it Off. The toggle will turn grey.
Your Mac will now hold the brightness level wherever you manually set it using the brightness keys (F1/F2 on a MacBook keyboard, or the slider in Control Centre) and will not change it automatically based on ambient light.
How to Turn Off Auto-Brightness on macOS Monterey and Earlier
If you are using macOS Monterey (12), Big Sur (11), or an older version with the classic System Preferences interface:
- Click the Apple menu () and select System Preferences.
- Click on the Displays icon.
- Ensure you are on the Display tab at the top of the window.
- Uncheck the box next to Automatically adjust brightness.
Why Does My Screen Still Dim When I Unplug the Charger?
If you have disabled the ambient light sensor but your screen still noticeably dims the moment you unplug your MacBook from its charger, this is a separate power-saving feature and not related to the ambient light sensor at all. macOS deliberately reduces screen brightness on battery power to extend your available charge time. Here is how to stop this behaviour:
- Disable “Slightly dim the display on battery”: Go to System Settings > Displays and click the Advanced… button at the bottom of the screen. Turn off the toggle labelled Slightly dim the display on battery.
- Disable Low Power Mode: Go to System Settings > Battery and change the Low Power Mode dropdown from “On Battery” or “Always” to Never. Low Power Mode aggressively throttles screen brightness to conserve battery.
After applying both of these changes, your MacBook’s display brightness should remain stable and consistent regardless of whether the charger is connected.