My screen is just too bright. How can I adjust screen brightness? So far I tried the following:

  1. "Brightness and lock" settings doesn't work.
  2. Fn + F6 or F7 doesn't work.
  3. This doesn't work.
  4. This doesn't work too.

My Laptop is Toshiba Satelite L745


You can try xrandr tool.

First run xrandr --verbose and look for a line with resolution like LVDS1 connected 1024x600+0+0. The name of your display (LVDS1 in this example) is needed here. Now you are ready to set brightness:

xrandr --output LVDS1 --brightness 0.4

xrandr sets software, not hardware brightness so you can exceed both upper and lower limits:

xrandr --output LVDS1 --brightness 1.7
xrandr --output LVDS1 --brightness -0.4  #negative value is also possible
xrandr --output LVDS1 --brightness 1
  • 2
    It still too bright. The way xrandr do is just filtering the colors Is there anyway to access hardware brightness?
    – Mas Bagol
    Feb 7 '15 at 7:00
  • For all that accessing the hardware brightness would be better, this was useful to me. Thanks.
    – mc0e
    Feb 19 '20 at 12:56

Before doing this, I installed firmware-linux-nonfree; I don't know whether that's affected anything.

If xbrightness does not detect the backlight, you'll need to find the backlight file and manually set the backlight value yourself. Here's the process I used for my Toshiba Satellite C50-B-14Z:

wizzwizz4@mylaptop:~$ ls /sys/class/
ata_device   devfreq   i2c-adapter    net           scsi_device   vc
ata_link     dma       ieee80211      pci_bus       scsi_disk     video4linux
ata_port     dmi       input          phy           scsi_generic  vtconsole
backlight    drm       iommu          powercap      scsi_host     watchdog
bdi          firmware  leds           power_supply  sound         wmi
block        gpio      mem            ppdev         spi_master
bluetooth    graphics  memstick_host  printer       thermal
bsg          hidraw    misc           rfkill        tpm
devcoredump  hwmon     mmc_host       rtc           tty
wizzwizz4@mylaptop:~$ ls /sys/class/backlight/
wizzwizz4@mylaptop:~$ ls /sys/class/backlight/intel_backlight/
actual_brightness  brightness  max_brightness  subsystem  uevent
bl_power           device      power           type

Now I've got the brightness file: /sys/class/backlight/intel_backlight/. I can read the value of this file:

wizzwizz4@mylaptop:~$ cat /sys/class/backlight/intel_backlight/brightness

3906?! That's way more than the usual maximum of 15! Checking the max_brightness file:

wizzwizz4@mylaptop:~$ cat /sys/class/backlight/intel_backlight/max_brightness

That... makes more sense. So it's about half-brightness at the moment. Well, I like it quite dim, so I'll set it to 390 out of 7812:

wizzwizz4@mylaptop:~$ echo 390 | sudo tee /sys/class/backlight/intel_backlight/brightness

And the screen dimmed! Yay!


I found the screen brightness solution in a somewhat obscure article. My issue was my laptop couldn't remember brightness settings upon reboot. I'll post the link at the end of my answer.

All that was needed was to edit the file /etc/rc.local and add one line.

First, back up the rc.local file.  If something goes wrong you can revert to the original file.

cat /etc/rc.local
#!/bin/sh -e
# rc.local
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
# In order to enable or disable this script just change the execution
# bits.
# By default this script does nothing.

# screen brightness line added
# it's to make the laptop remember settings at power up.

echo 7 > /sys/class/backlight/acpi_video0/brightness

exit 0

Note that I added the line echo 7 > /sys/class/backlight/acpi_video0/brightness to my rc.local file.

In my Debian Wheezy setup, the value echo 7 > … sets brightness midway between dark and bright. So 7 is perfect for me. Choose a value that suits you.

rc.local runs when you restart your machine.

Here's the link: Installing Ubuntu on Samsung 5 (SSD+HDD) | LinuxMeerkat

Scroll down the page to find how to change default screen brightness on a laptop.


For me on Acer 7530G with:

Distributor ID: Debian Description: Debian GNU/Linux 8.6 (jessie) Release: 8.6 Codename: jessie

The solution was in Application Menu> Settings> xfce4-desktop there can you set the brightness of the monitor, for me was 100 fine.


On my laptop Fn+Up and down is worked, you should try this.

  • 1
    Welcome to the site, and thank you for your contribution. Would you mind adding information on what OS flavor and version your laptop is running?
    – AdminBee
    Nov 20 '20 at 15:27

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