The quickest way to brighten your screen

Most computers let you adjust brightness using keyboard shortcuts or settings. On Windows, press the Windows key and the letter A together to open Quick Settings, then drag the brightness slider to the right. On a Mac, press the brightness-up key (usually marked with a sun icon on the top row of keys). If your keyboard doesn't have brightness keys, you can adjust it through your display settings instead.

If you're using an external monitor plugged into your computer, the brightness controls are usually physical buttons on the monitor itself, not on your keyboard. Look for buttons along the bottom or side of the monitor frame — they often have a sun icon or a plus sign.

Key Takeaways

  • Windows computers use the Quick Settings panel (Windows key + A) or Function keys to adjust brightness, while Macs use the brightness keys in the top row.
  • External monitors have physical buttons on the monitor frame itself, separate from your computer's keyboard controls.
  • If brightness keys don't work, check your keyboard settings to make sure they're not disabled or remapped to other functions.
  • Lowering your screen brightness can reduce eye strain during long work sessions and extend your laptop battery life.

Using Windows brightness controls

On Windows 10 and Windows 11, the fastest method is the Quick Settings panel. Hold down the Windows key (the one with the four squares) and press the letter A. A panel will slide in from the right side of your screen. Look for the brightness slider — it's usually near the top, marked with a sun icon. Drag it left to dim or right to brighten.

If Quick Settings doesn't appear, your keyboard may not have brightness keys mapped to it. Instead, go to Settings > System > Display and look for the brightness slider under "Brightness and color." You can also right-click on your desktop, select Display Settings, and adjust brightness from there.

Some Windows laptops use Function keys (Fn) combined with other keys to control brightness. Look at the top row of your keyboard for keys with sun icons. Hold Fn and press the sun key with an upward arrow to brighten, or the sun key with a downward arrow to dim. The exact keys vary by manufacturer — Dell, HP, Lenovo, and Asus all use slightly different layouts.

Using Mac brightness controls

On any Mac, look at the top row of your keyboard for the brightness keys. They look like a sun icon with lines radiating outward. The key on the left lowers brightness; the key on the right raises it. Press the right-side brightness key to brighten your screen. You'll see a brightness indicator appear on your screen as you adjust it.

If your Mac keyboard is wireless or older, it may not have physical brightness keys. Open System Settings, click Displays, and drag the brightness slider to the right. You can also use Spotlight search (Command + Space) to quickly jump to display settings.

Adjusting an external monitor's brightness

External monitors have their own brightness controls built into the monitor itself. Look along the bottom edge or the right side of the monitor frame for physical buttons. These are usually small, recessed buttons you press with your finger. One button typically opens an on-screen menu; others navigate through options or adjust brightness directly.

Press the menu button (often labeled with three horizontal lines or a gear icon) to see what controls are available. Use the arrow buttons to highlight "Brightness" and then press the plus or up button to increase it. The exact button layout varies by brand — Dell, LG, ASUS, and BenQ all arrange them differently, so check your monitor's manual if you're unsure which button does what.

Some newer monitors have touch-sensitive buttons instead of physical ones. If you can't find physical buttons, look for a touch-sensitive area along the bottom bezel of the monitor.

When brightness keys don't work

If your brightness keys aren't responding, the first step is to check whether they're disabled in your keyboard settings. On Windows, go to Settings > Devices > Keyboard and scroll down to see if there's an option for function key behavior. Some laptops let you toggle between "Fn Lock" mode (where brightness keys work) and regular mode (where they control other functions). Press Fn and Escape together to toggle Fn Lock on and off.

On a Mac, go to System Settings > Keyboard and check whether "Use F1, F2, etc. as standard function keys" is turned on. If it is, your brightness keys may be mapped to other functions instead. Turn that setting off to restore brightness control.

If you've checked these settings and brightness keys still don't work, your keyboard driver may need updating. On Windows, right-click the Start menu, select Device Manager, expand Keyboards, right-click your keyboard, and select Update Driver. On a Mac, brightness key issues are rare, but restarting your computer usually fixes them.

Why you might want to adjust brightness

Lowering your screen brightness can reduce eye strain during long work sessions, especially in dim rooms. A good rule is to match your screen brightness to the brightness of your surroundings — if you're in a dark room, dim your screen; if you're in bright sunlight, raise it. Many people find that brightness around 40 to 60 percent feels comfortable indoors.

On laptops, lowering brightness also extends battery life. Your screen uses a significant amount of power, so dimming it can add an hour or more to your battery runtime. If you're working unplugged, this is worth doing.

Using automatic brightness adjustment

Both Windows and Mac computers can adjust brightness automatically based on the light in your room, if your device has a light sensor. On Windows 11, go to Settings > System > Display and turn on "Brightness" under "Brightness and color." On Windows 10, the setting is called "Change brightness automatically" and is in Settings > System > Display.

On a Mac, go to System Settings > Displays and check the box next to "Automatically adjust brightness." This feature works on most modern Macs with built-in displays. If you're using an external monitor, automatic brightness usually won't work because most external monitors don't have light sensors.

Frequently Asked Questions

Why is my screen so dim even when I turn brightness all the way up?

Your display may be set to a low maximum brightness in settings, or your screen may be damaged. On Windows, check Settings > System > Display and look for any brightness limiter. On a Mac, make sure you're not in Low Power Mode, which caps brightness. If brightness is already at maximum in settings, your screen's backlight may be failing and you may need professional repair.

Can I adjust brightness differently for different apps?

No — brightness is a hardware setting that affects your entire display, not individual programs. However, some apps like web browsers let you adjust text size or background color, which can reduce eye strain without changing screen brightness.

Does lowering brightness damage my screen?

No. Lowering brightness actually extends your screen's lifespan by reducing heat and wear on the backlight. There's no downside to running your screen at lower brightness levels.

My external monitor has no buttons — how do I adjust brightness?

Some monitors use on-screen menus controlled by touch-sensitive areas instead of physical buttons. Look for a touch-sensitive strip along the bottom or side bezel. If your monitor truly has no controls, check the manual to see if brightness is adjustable through USB or DisplayPort settings on your computer instead.

Will adjusting brightness help my battery last longer?

Yes, significantly. Screen brightness is one of the largest power drains on a laptop. Lowering brightness from maximum to 50 percent can add one to two hours of battery life, depending on your laptop model.