The fastest way to adjust brightness depends on your device

On Windows, use the keyboard shortcut Windows key + A to open Quick Settings, then drag the brightness slider. On a Mac, press F1 to dim or F2 to brighten — or open System Settings, go to Displays, and adjust the slider. On a Chromebook, press the brightness keys on your keyboard (usually marked with sun symbols) or swipe down from the top to access Quick Settings.

If your monitor has physical buttons on the frame itself, you can also adjust brightness directly without touching your computer. This method works the same way on any device — look for buttons or a dial on the bottom or side of the monitor, usually labeled with a sun icon or brightness symbol.

The method you use depends on whether you want to change the brightness of your computer's screen or an external monitor plugged into your computer. Built-in laptop screens respond to keyboard shortcuts and system settings. External monitors usually need their own physical controls, though some newer USB-C monitors can be adjusted through your computer.

Key Takeaways

  • Windows users can open Quick Settings with Windows key + A and drag the brightness slider, or use Fn + brightness keys on the keyboard.
  • Mac users press F1 to dim or F2 to brighten, or adjust brightness in System Settings under Displays.
  • Chromebook brightness is controlled by dedicated keys on the keyboard marked with sun symbols, or through Quick Settings.
  • External monitors have physical buttons or dials on the frame that control brightness independently of your computer's settings.
  • If your monitor has no physical controls and is not USB-C compatible, you may not be able to adjust it from your computer.

Adjusting brightness on Windows

The quickest method on Windows 10 or 11 is to use the Quick Settings panel. Press Windows key + A at the same time. A panel will slide in from the right side of your screen. Look for the brightness slider — it usually shows a sun icon and sits near the top of the panel. Drag the slider left to dim the screen or right to brighten it. The change takes effect when ready.

If your keyboard has dedicated brightness keys, you can also use those. Look for keys with sun symbols, usually in the top row. Press the key with the dimmer sun to reduce brightness, or the brighter sun to increase it. You may need to hold the Fn key at the same time, depending on your keyboard model. A brightness indicator will appear on your screen showing the current level.

For more detailed control, open Settings by pressing Windows key + I. Go to System, then Display. Under Brightness and color, you will see a brightness slider. This method gives you the same result as Quick Settings but takes a few more steps. Some Windows computers also let you set brightness to change automatically based on the time of day — look for "Adaptive brightness" in the same Display settings.

Adjusting brightness on Mac

The simplest way on a Mac is to use the brightness keys on your keyboard. Press F1 to dim the screen or F2 to brighten it. Each press moves the brightness up or down one level. You will see a brightness indicator appear on your screen. If these keys do not work, your keyboard may require you to hold the Fn key first — press Fn + F1 or Fn + F2.

You can also adjust brightness through System Settings. Click the Apple menu in the top left corner, then select System Settings. Go to Displays. You will see a brightness slider. Drag it left to dim or right to brighten. This method is useful if you want to set a specific brightness level or if your keyboard keys are not working.

Mac laptops also have a feature called "Adaptive brightness" that adjusts the screen based on the light in your room. You can turn this on or off in the same Displays settings. If you use an external monitor connected to your Mac, the brightness keys and System Settings will only control your Mac's built-in screen — you will need to use the monitor's physical buttons to adjust the external display.

Adjusting brightness on Chromebook

Chromebooks have dedicated brightness keys on the keyboard, usually in the top row. Look for keys with sun symbols — one dimmer and one brighter. Press the dimmer sun to reduce brightness or the brighter sun to increase it. A brightness indicator will appear on your screen. This is the fastest way to adjust brightness on a Chromebook.

If you prefer to use the settings menu, swipe down from the top of your screen to open Quick Settings. You will see a brightness slider in the panel that appears. Drag it left to dim or right to brighten. This method works the same way as the keyboard keys but may be slower if you are already typing.

Chromebooks do not have as many brightness customization options as Windows or Mac computers. You cannot usually set automatic brightness adjustment based on time of day. If your Chromebook has an external monitor attached, the brightness keys will only control the Chromebook's built-in screen — use the monitor's physical buttons to adjust the external display.

Using your monitor's physical controls

Most external monitors have physical buttons or a dial on the frame that control brightness without needing your computer. Look on the bottom edge, the side, or the back of the monitor for buttons marked with a sun icon or the word "brightness." Some monitors have a single dial you turn, while others have separate buttons for increase and decrease.

Press or turn the brightness control to adjust the display. You will usually see a brightness indicator appear on the screen itself. This method works on any computer — Windows, Mac, or Chromebook — because the monitor controls its own brightness independently. If your monitor is very old, the controls might be labeled differently or harder to find, but the sun icon is the standard symbol across most brands.

Using the monitor's physical controls is often the best choice for external displays because it does not depend on your computer's operating system or drivers. If your monitor has no physical buttons and is not a newer USB-C model, you may not be able to adjust brightness from your computer at all — the monitor's own controls are your only option.

Adjusting brightness for USB-C monitors

Some newer monitors that connect via USB-C can be adjusted through your computer instead of physical buttons. These monitors are less common but becoming more available. If your monitor supports this feature, you can adjust brightness through your computer's settings the same way you would adjust a built-in screen.

On Windows, open Quick Settings (Windows key + A) and use the brightness slider. On Mac, use the F1 and F2 keys or go to System Settings and Displays. On Chromebook, use the brightness keys or Quick Settings. The monitor will respond to these commands because the USB-C connection carries both power and display data, allowing your computer to control the monitor's settings.

Check your monitor's manual or the manufacturer's website to confirm whether it supports brightness adjustment through USB-C. Not all USB-C monitors have this feature — some still require physical buttons. If your monitor came with software to install, that software may also let you adjust brightness from your computer.

Troubleshooting brightness that will not change

If your brightness slider is grayed out or does not respond, your computer may not recognize the monitor or may be missing drivers. On Windows, open Device Manager by right-clicking the Start menu and selecting Device Manager. Look for Display adapters and expand that section. If you see a yellow warning icon, right-click it and select Update driver. Windows will search for the latest version.

On Mac, brightness controls usually work without drivers, but if the F1 and F2 keys do not work, restart your Mac. If the problem continues, go to System Settings, Displays, and check whether the brightness slider is available. If it is grayed out, your Mac may have a hardware issue.

For external monitors, always check the physical buttons first — they do not depend on your computer's software. If the monitor's own brightness controls do not work, the monitor itself may have a problem. If you are using a USB-C monitor and the brightness slider in your computer's settings does not work, try unplugging the USB-C cable and plugging it back in, or restart your computer.

Frequently Asked Questions

Why is my brightness slider missing from Windows settings?

Windows hides the brightness slider if your computer does not have a brightness sensor or if the display driver is outdated. Open Device Manager, expand Display adapters, right-click your graphics card, and select Update driver. If that does not work, your computer may not support software brightness control — use your monitor's physical buttons instead.

Can I adjust an external monitor's brightness from my computer?

Only if the monitor is a newer USB-C model that supports remote control, or if it came with special software. Most external monitors require you to use their physical buttons. Check your monitor's manual or the manufacturer's website to confirm whether it supports brightness adjustment through your computer.

What should I do if my monitor's brightness buttons are not working?

First, make sure you are pressing the correct buttons — they are usually marked with a sun icon on the monitor's frame. If the buttons still do not respond, the monitor may need a restart. Unplug the monitor's power cable for 30 seconds, then plug it back in. If that does not work, the monitor may have a hardware problem.

Does adjusting brightness affect my monitor's lifespan?

No. Changing brightness does not damage your monitor or reduce how long it lasts. Monitors are designed to operate at any brightness level. Running your monitor at lower brightness may slightly reduce power use, but this is a minor effect and does not harm the display.

Why does my Mac brightness keep changing on its own?

Your Mac likely has Adaptive brightness turned on. This feature automatically adjusts brightness based on the light in your room. Go to System Settings, Displays, and look for an Adaptive brightness toggle. Turn it off if you prefer to control brightness manually.