The fastest way depends on your device and operating system

On Windows, use the keyboard shortcut Fn + brightness keys — usually the up and down arrow symbols on your function row. On Mac, press the brightness keys in the top row (they look like a sun with lines). On Linux, the method varies by desktop environment, but Ubuntu uses Fn + brightness keys the same way Windows does. If keyboard shortcuts don't work, you can adjust brightness through your system settings instead.

Some monitors have physical buttons on the bezel itself, usually near the power button. These let you change brightness without touching your computer at all. Laptop screens almost always respond to keyboard shortcuts first, since that's the fastest option when you're working.

Key Takeaways

  • Windows and most Linux systems use Fn + brightness keys (usually arrow symbols) to adjust screen brightness instantly.
  • Mac laptops use dedicated brightness keys in the top row of the keyboard, marked with sun symbols.
  • If keyboard shortcuts don't work, you can adjust brightness through Settings on Windows, System Preferences on Mac, or your display settings on Linux.
  • External monitors often have physical buttons on the front or side that control brightness independently of your computer.
  • Brightness adjustment on a laptop affects only that screen, while external monitor brightness is controlled separately.

Windows brightness adjustment

The quickest method on Windows is the Fn key plus brightness keys. Look at your keyboard's function row (the top row with F1, F2, etc.). Two of those keys will have brightness symbols — usually a sun with fewer lines for decrease and more lines for increase. Hold Fn and press the appropriate key repeatedly until the brightness reaches what you want. A brightness slider appears on screen to show your progress.

If your keyboard doesn't have brightness keys, or if they don't work, open Settings by pressing Windows key + I. Go to System, then Display. Under "Brightness and color," you'll see a brightness slider. Drag it left to darken or right to brighten. This method takes a few seconds longer but works on any Windows machine.

Some Windows laptops also let you adjust brightness from the Action Center. Swipe in from the right edge of the screen (or press Windows key + A) and look for a brightness slider. This is faster than opening Settings but slower than using keyboard shortcuts.

Mac brightness adjustment

On Mac laptops, look at the top row of your keyboard for keys with sun symbols. The key with fewer lines decreases brightness; the key with more lines increases it. Press either key and the brightness changes immediately. A brightness indicator appears on screen. Unlike Windows, Mac doesn't require the Fn key — just press the brightness key directly.

If those keys don't work, open System Preferences (or System Settings on newer Macs). Click Displays. You'll see a brightness slider. Drag it to adjust. Some Macs also have an Auto-brightness option that adjusts the screen based on ambient light — toggle this on or off depending on whether you want automatic adjustment.

Mac also lets you adjust brightness from Control Center. Click the Control Center icon in the top-right corner of the menu bar and look for the brightness slider. This is faster than opening System Preferences but slower than using the keyboard keys.

Linux brightness adjustment

On Ubuntu and most common Linux distributions, use Fn + brightness keys the same way as Windows. The brightness keys are usually arrow symbols on your function row. Hold Fn and press the up or down arrow key to increase or decrease brightness. A brightness indicator appears on screen.

If keyboard shortcuts don't work, the method depends on your desktop environment. On GNOME (used by Ubuntu), click the system menu in the top-right corner and look for a brightness slider. On KDE Plasma, open System Settings and navigate to Startup and Shutdown, then Splash Screen or Display and Monitor depending on your version. Some Linux systems require opening a terminal and using command-line tools, but this is rarely necessary on modern distributions.

If you're using a custom Linux setup or older distribution, brightness control may not be available through the graphical interface. In that case, you can adjust it through the terminal using commands like xrandr or by editing configuration files, but this is beyond what most users need to do.

External monitor brightness control

External monitors have their own brightness settings separate from your laptop or desktop. Look for physical buttons on the monitor's bezel — usually near the power button on the front or side. These buttons open an on-screen menu where you can adjust brightness, contrast, and other display settings. The exact button layout varies by manufacturer, so check your monitor's manual if you can't find the controls.

Some monitors also let you adjust brightness through software. Manufacturers like Dell, LG, and ASUS provide apps that let you control brightness from your computer instead of using physical buttons. These apps are optional — the physical buttons always work — but they're convenient if you adjust brightness frequently.

If your monitor is very old or uses a VGA connection, it may not have brightness controls at all. In that case, you're limited to adjusting your computer's overall display settings, which affects how bright the image appears but doesn't change the monitor's internal brightness level.

When brightness keys don't work

If your keyboard shortcuts aren't working, first check whether your keyboard driver is up to date. On Windows, open Device Manager (right-click the Start button and select it), expand Keyboards, right-click your keyboard, and select Update driver. On Mac, brightness keys usually work without drivers, so if they don't, restart your computer first.

Some laptops require you to hold Fn to use function keys, while others have it reversed — the function keys work by default and you hold Fn to use the regular symbols. Check your keyboard's settings. On Windows, go to Settings > System > Display, scroll down, and look for a "Function key row" or "Fn key" option. On Mac, open System Preferences > Keyboard and look for an option about function keys.

If brightness keys still don't work after updating drivers and checking settings, your keyboard may be damaged or your laptop's brightness sensor may not be functioning. In that case, use the Settings method described above, which works regardless of keyboard hardware.

Brightness and eye strain

Brightness that's too high can cause eye strain, especially in dark rooms. Brightness that's too low makes text hard to read. A good starting point is to set your screen brightness so it's roughly as bright as your surroundings — if you're in a dark room, dim the screen; if you're outside or near a window, brighten it. Many people find that 40 to 60 percent brightness works well indoors.

If you adjust brightness frequently, consider enabling auto-brightness on your laptop. This feature uses an ambient light sensor to adjust brightness automatically as the light around you changes. On Mac, this is called "Auto-brightness" in Display settings. On Windows, it's called "Adaptive brightness" in Display settings. Auto-brightness isn't perfect — it sometimes adjusts when you don't want it to — but many people find it reduces the need to manually adjust throughout the day.

Frequently Asked Questions

Why do my brightness keys show a symbol but don't change the brightness?

Your keyboard driver may be outdated or your Fn key settings may be reversed. Update your keyboard driver through Device Manager on Windows, or check your Fn key settings in System Preferences on Mac. If that doesn't work, use your Settings menu to adjust brightness instead — that method works on any device.

Can I adjust brightness on an external monitor from my computer?

Some monitors include software that lets you control brightness from your computer, but most require using the physical buttons on the monitor itself. Check your monitor's manual or the manufacturer's website to see if they offer a control app. Physical buttons always work regardless of software.

Does adjusting brightness on my laptop affect an external monitor?

No. Laptop brightness and external monitor brightness are separate. Adjusting your laptop's brightness only affects the laptop screen. To change an external monitor's brightness, use its physical buttons or its control software.

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

Yes. Windows has a feature called "Night light" that reduces blue light in the evening, and you can pair this with auto-brightness to adjust overall brightness automatically. Mac has "Night Shift" for the same purpose. Both systems also support scheduling these features to turn on and off at specific times.

What if my monitor has no brightness buttons and no software?

Older monitors sometimes lack brightness controls entirely. In that case, you're limited to adjusting your computer's display settings, which affects the image brightness but not the monitor's internal light output. If the image is too dim, you may need to replace the monitor.