How to Adjust Monitor Brightness on Ubuntu
Controlling your monitor’s brightness on Ubuntu can help reduce eye strain and save battery life. This guide will show you how to check and change your monitor’s brightness using both built-in system files and the brightnessctl
tool.
Checking Current Brightness
To see your current monitor brightness value, run:
cat /sys/class/backlight/*/brightness
This command outputs a number representing the current brightness level. To find out the maximum possible brightness, use:
cat /sys/class/backlight/*/max_brightness
You can calculate the current brightness as a percentage with:
current=$(cat /sys/class/backlight/*/brightness)
max=$(cat /sys/class/backlight/*/max_brightness)
echo $(( 100 * current / max ))%
Example output:
40
100
40%
Changing Brightness Manually
To set the brightness to a specific value, write a number (e.g., 0 or 100) to the brightness file. You need sudo
for this:
echo 50 | sudo tee /sys/class/backlight/*/brightness
If you want to set the brightness by percentage, calculate the value based on the maximum brightness.
Using brightnessctl
to Control Brightness
The brightnessctl
tool provides a simpler way to manage brightness.
Install brightnessctl
sudo apt-get install brightnessctl
Check Current Brightness
brightnessctl info
Expected output:
Device 'amdgpu_bl1' of class 'backlight':
Current brightness: 255 (100%)
Max brightness: 255
This command displays information about your current brightness level and the maximum brightness supported by your monitor.
Set Brightness by Value or Percentage
To set a specific value:
brightnessctl set 10 # Set brightness to 10 (about 4%)
Expected output:
Updated device 'amdgpu_bl1':
Device 'amdgpu_bl1' of class 'backlight':
Current brightness: 10 (4%)
Max brightness: 255
To set by percentage:
brightnessctl set 10%
Expected output:
Updated device 'amdgpu_bl1':
Device 'amdgpu_bl1' of class 'backlight':
Current brightness: 26 (10%)
Max brightness: 255
By following these steps, you can easily check and adjust your monitor’s brightness on Ubuntu, making your screen more comfortable for your eyes and your workflow.