The quickest way to change brightness on any computer

The fastest method depends on your device. On Windows laptops, press the Fn key and the brightness keys (usually marked with a sun icon) at the top of your keyboard — hold Fn and tap the key with the sun getting brighter to increase brightness, or the dimmer sun to decrease it. On Mac laptops, press the brightness keys in the top row without needing Fn. On desktop computers without dedicated brightness keys, you'll use the Settings menu instead.

If your keyboard has brightness keys but they don't work, your laptop may need the correct driver installed, or the function keys may be locked. Check whether a light bulb icon appears on your Fn key — if it does, you may need to hold Fn while pressing the brightness key, or toggle Fn Lock first by pressing Fn and Esc together.

Key Takeaways

  • Laptop brightness keys are usually in the top row and marked with a sun icon; hold Fn and press them to adjust on Windows machines.
  • Mac laptops have dedicated brightness keys in the top row that work without holding any modifier key.
  • Desktop monitors have brightness controls on the physical monitor itself, typically buttons or a menu on the front or side.
  • If brightness keys don't respond, check your keyboard drivers in Device Manager (Windows) or System Preferences (Mac).
  • Adjusting brightness in Settings gives you finer control and works on any computer, though it's slower than using hardware keys.

Adjusting brightness through Windows Settings

Open the Settings app by pressing Windows key + I, then click System in the left menu. Select Display, and you'll see a brightness slider under "Brightness and color." Drag the slider left to dim the screen or right to brighten it. The change takes effect when ready.

You can also reach this same slider faster by clicking the battery icon in your system tray (bottom right corner), then clicking Brightness to expand the brightness control. This method skips the Settings app entirely and is useful if your keyboard brightness keys aren't working.

Adjusting brightness on a Mac

Press the brightness keys in the top row of your keyboard — they look like a sun with lines. The key on the left dims the screen; the key on the right brightens it. Hold the key down to adjust continuously, or tap it once for a small change. You'll see a brightness indicator appear on screen showing your current level.

If you want more control, open System Settings (click the Apple menu, then System Settings), click Displays, and drag the brightness slider. On newer Macs with an M1 or M2 chip, you may also see an option for "Automatic brightness" — turning this on lets your Mac adjust brightness based on ambient light in the room.

Adjusting brightness on a desktop monitor

Desktop monitors have physical brightness controls separate from your computer. Look for buttons or a dial on the front or side of your monitor — usually near the bottom edge. Press the menu button (often marked with lines or a square) to open the on-screen menu, then use the arrow buttons to navigate to "Brightness" or "Contrast." Use the plus and minus buttons to adjust, then press menu again to close.

Some monitors have a single dial or rocker switch instead of buttons. Turn or rock it left to dim and right to brighten. If you can't find physical controls, your monitor may use a USB connection to a software app on your computer — check the manufacturer's website for the control software if the monitor came with a disc or manual.

Fixing brightness keys that don't work

On Windows, open Device Manager by right-clicking the Start button and selecting it from the menu. Expand Keyboards, right-click your keyboard, and select Update driver. Choose Search automatically for updated driver software and let Windows search. If an update is found, install it and restart your computer.

If updating the driver doesn't help, check whether your laptop has an Fn Lock feature. Press Fn + Esc together — this toggles whether the Fn key is locked on or off. When Fn Lock is on, you may need to hold Fn to use brightness keys; when it's off, the brightness keys work without Fn. Try both settings to see which one works for your keyboard.

On a Mac, brightness keys rarely fail, but if they don't work, restart your computer first. If the problem persists, open System Settings, click Keyboard, then Keyboard Shortcuts, and check that Display is enabled on the left side. If it's unchecked, click it to turn it back on.

When to use automatic brightness

Both Windows and Mac offer automatic brightness adjustment, which dims your screen in dark rooms and brightens it in bright light. On Windows, open Settings > System > Display and toggle Adaptive brightness on. On Mac, go to System Settings > Displays and turn on Automatic brightness. This feature reduces eye strain and saves battery life on laptops.

Automatic brightness works best if your computer has an ambient light sensor — most modern laptops do, but older desktops may not. If you find automatic brightness annoying because it changes too often, you can turn it off and adjust manually instead. There's no performance cost to leaving it on; you can straightforward ignore it and adjust brightness yourself whenever you want.

Frequently Asked Questions

Why is my brightness stuck at maximum or minimum?

Check whether Fn Lock is on by pressing Fn + Esc. If brightness keys still don't work, update your keyboard driver in Device Manager (Windows) or restart your Mac. If the problem continues, your monitor or display panel may have a hardware fault — contact the manufacturer or a repair technician.

Can I set different brightness levels for different times of day?

Yes. Windows has a feature called "Night light" that reduces blue light in the evening; go to Settings > System > Display and toggle it on, then set a schedule. Mac has "Night Shift" in System Settings > Displays. Both dim your screen automatically at sunset and brighten it at sunrise, reducing eye strain before bed.

Does lowering brightness actually save battery on a laptop?

Yes, significantly. The display uses more power than any other component on a laptop. Lowering brightness by 50 percent can extend battery life by one to two hours depending on your model. Turning on automatic brightness or using Night light also helps because both reduce the brightness level most of the time.

What if my monitor has no brightness buttons?

Check the back of the monitor for a USB cable connected to your computer — some monitors use software control instead of physical buttons. Look for a disc or manual that came with the monitor, or visit the manufacturer's website and search for your model number to read the control software.