To change screen brightness on a Chromebook, press the brightness keys in the top row of the keyboard. The key with the small sun lowers brightness and the key with the large sun raises it. You can also drag the brightness slider in Quick Settings, which opens when you click the time in the bottom-right corner.
Before you start
- Applies to: All Chromebooks running ChromeOS.
- You need: Nothing extra. Brightness control is built in.
- Time: Under a minute.
How do I change brightness with the keyboard?
The brightness keys sit in the top row of every Chromebook keyboard, and they are the fastest way to adjust the screen.
- Find the two keys marked with a sun icon in the top row. The smaller sun is dimmer, the larger sun is brighter.
- Press the smaller sun key to lower the screen brightness one step at a time.
- Press the larger sun key to raise it.
- Hold either key down to move through the brightness range faster.
How do I change brightness from Quick Settings?
Quick Settings gives you a slider, which is handy if you want a precise level or your keyboard is not available.
- Click the time in the bottom-right corner of the screen to open Quick Settings.
- Find the brightness slider in the panel. It is the one with the sun icon.
- Drag it to the left to lower the brightness.
- Drag it to the right to increase the brightness.
How do I turn adaptive brightness on or off?
Adaptive brightness lets ChromeOS set the screen level for you based on the light in the room.
- Open Settings.
- Go to Device, then Displays.
- Look for the Adaptive brightness toggle and switch it on or off.
Not every Chromebook has this option. It only appears on devices with an ambient light sensor.
Why is my Chromebook brightness not working?
Warning: A powerwash erases everything stored locally on the Chromebook. Back up your files first.
- Sign out and sign back in as a Guest, then test the brightness keys and the slider again.
- If brightness works in Guest mode, the problem is in your profile. Back up your files and powerwash the Chromebook, then test again.
- If brightness still does not work after a powerwash, contact your Chromebook manufacturer. It is most likely a hardware fault.
Quick tips
- If your Chromebook has a backlit keyboard, hold Alt while pressing the brightness keys. That adjusts the keyboard backlight instead of the screen.
- Lowering brightness is one of the simplest ways to stretch Chromebook battery life.
Older auto-brightness behaviour, for reference
On devices without the adaptive brightness toggle, older versions of ChromeOS used a simpler rule based on power source and ambient light. This table is kept here as historical reference.
| Power source | Direct sunlight (>= 400 lux) | Normal ambient light |
|---|---|---|
| AC | 100% (100% linear) | 80% (~62% linear) |
| Battery | 80% (~62% linear) | 63% (~37% linear) |
The original Pixelbook had a finer-grained sensor with 7 distinct auto-brightness levels, also listed for reference.
| Situation | Lux Step Down | Lux Step Up | Brightness UI | Brightness Linear |
|---|---|---|---|---|
| Low light | N/A | 90 | 36.14% | 10.75% |
| Indoor – normal | 40 | 250 | 47.62% | 20.00% |
| Indoor – bright | 180 | 360 | 60.57% | 34.00% |
| Outdoor – dark | 250 | 500 | 71.65% | 49.00% |
| Outdoor – overcast | 350 | 1700 | 85.83% | 72.24% |
| Outdoor – clear sky | 1100 | 7000 | 93.27% | 86.25% |
| Direct sunlight | 5000 | N/A | 100.00% | 100.00% |
Frequently asked questions
Which keys control brightness on a Chromebook?
The two sun keys in the top row of the keyboard. The key with the smaller sun lowers brightness and the key with the larger sun raises it.
How do I change the keyboard backlight brightness?
Hold the Alt key while pressing the screen brightness keys. This only works on Chromebooks that have a backlit keyboard.
Why does my Chromebook screen brightness keep changing on its own?
Adaptive brightness is switched on. Go to Settings, Device, Displays and turn off Adaptive brightness to control the level yourself.
Can I set brightness on an external monitor from ChromeOS?
No. The ChromeOS brightness controls apply to the built-in display. Use the buttons on the external monitor itself.
Related guides
- How to Rotate the Screen on a Chromebook
- How to Use Ambient Mode on a Chromebook
- 100+ Chromebook Keyboard Shortcuts
Screen brightness on a Chromebook takes seconds to change, whether you use the sun keys, the Quick Settings slider, or adaptive brightness. If none of them respond, the Guest account test will tell you quickly whether the fault is in your profile or the hardware.
