The fastest way to change brightness

On most Windows 10 laptops and tablets, you can adjust brightness using the keyboard shortcut keys on the top row of your keyboard. Look for keys with a sun symbol — one with a dimmer sun lowers brightness, one with a brighter sun raises it. Hold the Fn key (usually in the bottom left corner) and press the brightness key to change the setting when ready.

If your keyboard does not have brightness keys, or if you prefer using your mouse, Windows 10 has a built-in brightness slider in the Quick Settings menu. Press Windows key + A together, and a panel will open on the right side of your screen. Look for the brightness slider — it usually appears as a sun icon with a bar underneath. Drag the slider left to dim the screen or right to brighten it.

Desktop computers with external monitors do not use Windows brightness controls. Instead, look for physical buttons on the front or side of your monitor itself, usually labeled with a sun symbol or a plus and minus sign. These buttons control the monitor's own brightness setting.

Key Takeaways

  • Laptops and tablets use keyboard shortcut keys (Fn + brightness key) or the Quick Settings panel (Windows key + A) to adjust brightness.
  • Desktop monitors have physical buttons on the monitor itself that control brightness — Windows settings do not affect them.
  • If Quick Settings does not show a brightness slider, your device may not have a brightness sensor or may need a driver update.
  • You can also adjust brightness through Settings > System > Display if you want finer control or need to troubleshoot.

Using the Settings menu for more control

If you want to set brightness to a specific level or troubleshoot brightness problems, the Settings menu gives you more options. Open Settings by pressing Windows key + I, then click System in the left sidebar, and select Display.

Under the Display settings, scroll down until you see Brightness and color. You will see a brightness slider that works the same way as the Quick Settings slider — drag it left to dim or right to brighten. This menu also shows you whether Adaptive brightness is turned on. Adaptive brightness automatically adjusts your screen based on the light in the room around you, using your device's built-in light sensor. If you find the brightness changing on its own, you can toggle this setting off here.

The Settings menu is also where you can check if your device is set to use battery saver mode, which often reduces brightness to save power. If you are on battery power and your screen seems dimmer than usual, look for Battery saver in the left sidebar and check whether it is currently active.

When brightness keys do not work

If your keyboard brightness keys do nothing, the most common reason is that your device needs a driver update. A driver is software that tells Windows how to communicate with your keyboard or brightness sensor. Without the right driver, Windows cannot receive the signal from your brightness keys.

To check for driver updates, press Windows key + X and select Device Manager. Look for a category called Keyboards or Human Interface Devices and click the arrow next to it to expand the list. If you see a yellow warning triangle next to any item, right-click it and select Update driver. Windows will search for the latest version online.

If there is no warning triangle but your brightness keys still do not work, try restarting your computer. Sometimes a fresh start resets the connection between your keyboard and Windows. If brightness keys still do not respond after a restart and a driver update, the keyboard hardware itself may need replacement, or your device may not have a brightness sensor built in.

Brightness and eye strain

Brightness level is personal — what feels comfortable depends on the light in your room and your own eyes. A screen that is too bright can cause glare and eye fatigue, especially in a dark room. A screen that is too dim forces your eyes to work harder to read text.

A common starting point is to set your brightness so that your screen is roughly as bright as the surfaces around it. If you are in a bright room, you may need higher brightness. If you are in a dark room, lower brightness usually feels more comfortable. Many people find that turning on Night light (also in Display settings) reduces eye strain in the evening by shifting your screen toward warmer colors.

If you adjust brightness and still experience eye strain, the problem may not be brightness alone. Screen distance, text size, and how often you take breaks all matter. Moving your screen to arm's length away and taking a 20-second break every 20 minutes to look at something far away can make a real difference.

Brightness on external monitors

If you have connected an external monitor to your Windows 10 computer, that monitor has its own brightness control separate from your laptop or desktop settings. Look for physical buttons on the monitor itself — usually on the front bezel or along the bottom edge. These buttons typically have a sun symbol or a plus and minus sign.

Press and hold the button or use the arrow buttons to navigate to a brightness menu on the monitor's built-in display. Adjust the brightness using the same buttons, then press the button again to close the menu. Each monitor brand works slightly differently, so if you cannot find the buttons, check the back of your monitor for a model number and search online for the manual.

Some newer monitors support brightness control through Windows if they are connected via USB-C or DisplayPort and have the right driver installed. This is less common, but if your monitor came with software or a driver disc, installing it may add brightness controls to your Windows Display settings. Check your monitor's manual or the manufacturer's website to see if this applies to your model.

Brightness and battery life

Lowering your screen brightness is one of the most effective ways to extend battery life on a laptop or tablet. A bright screen uses significantly more power than a dim one. If you are working on battery power and want your device to last longer, reducing brightness is usually the first step.

Windows 10 can help automate this. In Settings > System > Display, you can turn on Adaptive brightness to let Windows lower brightness automatically when you are on battery power. You can also enable Battery saver mode, which reduces brightness along with other power-saving changes. Battery saver mode typically activates automatically when your battery reaches 20 percent, but you can turn it on manually at any time by clicking the battery icon in your system tray.

Frequently Asked Questions

Why does my brightness keep changing on its own?

Adaptive brightness is most likely the cause. This feature uses your device's light sensor to adjust brightness based on your surroundings. Open Settings > System > Display and scroll down to Brightness and color. Toggle off Adaptive brightness to stop automatic changes. If you are on battery power, Battery saver mode may also be lowering brightness — check Settings > System > Battery saver to see if it is active.

Can I adjust brightness on an external monitor using Windows?

Most external monitors require physical buttons on the monitor itself. However, some newer monitors connected via USB-C or DisplayPort may support brightness control through Windows if the manufacturer's driver is installed. Check your monitor's manual or the manufacturer's website to see if your model supports this. If not, use the physical buttons on your monitor to adjust brightness.

My brightness slider is missing from Quick Settings. What do I do?

This usually means your device does not have a brightness sensor or the driver is not installed correctly. Try opening Settings > System > Display and looking for the brightness slider there instead. If it is also missing from Display settings, check Device Manager for driver updates under Keyboards or Human Interface Devices. If you still see no brightness option, your device may not have the hardware to support brightness adjustment.

Does lowering brightness really save battery?

Yes. Your screen is one of the biggest power consumers on a laptop or tablet. Lowering brightness to a comfortable level can extend battery life by 30 minutes or more, depending on how much you lower it. Turning on Adaptive brightness or Battery saver mode automates this for you when you are running on battery power.

Is there a way to set different brightness levels for different times of day?

Windows 10 does not have a built-in scheduler for brightness, but Night light (in Display settings) automatically shifts your screen toward warmer colors in the evening, which many people find easier on the eyes. You can set a schedule for Night light to turn on and off at specific times. For more advanced scheduling, you would need third-party software, though the built-in Quick Settings slider is usually fast enough for manual adjustments throughout the day.