The quickest way to dim your screen

On most computers, you can lower brightness using keyboard shortcuts or your system settings. The fastest method depends on whether you use Windows or Mac, and whether your keyboard has dedicated brightness keys.

If your keyboard has brightness keys — usually marked with a sun symbol and located on the function row at the top — press the key with the dimmer sun. On Windows laptops, this is often Fn + the brightness-down key. On Mac laptops, press the brightness-down key directly without holding Fn. The screen will dim in steps each time you press it.

If your keyboard has no brightness keys, or if the keys do not work, you can adjust brightness through your system settings instead. This takes a few more clicks but works on any computer.

Key Takeaways

  • Brightness keys on your keyboard (marked with a sun symbol) are the fastest way to dim your screen on most laptops.
  • Windows and Mac handle brightness keys differently — Windows usually requires holding Fn, while Mac does not.
  • If your keyboard has no brightness keys, you can lower brightness through Display settings in Windows or System Preferences on Mac.
  • Desktop computers connected to an external monitor have brightness controls on the monitor itself, usually buttons on the back or side.

Adjusting brightness in Windows settings

Open the Settings app by pressing Windows key + I, or click the Start menu and type "Settings". Once Settings opens, click System in the left sidebar, then click Display.

Under the "Brightness and color" section, you will see a slider labeled "Brightness". Drag it to the left to dim the screen or to the right to brighten it. The change takes effect when ready. You can also use the quick settings panel: press Windows key + A to open it, and you will see a brightness slider at the top.

Some Windows laptops also let you set brightness to change automatically based on the time of day. In the Display settings, look for an option called "Night light" — turning this on makes the screen warmer and dimmer in the evening, which can reduce eye strain.

Adjusting brightness on a Mac

On a Mac laptop, the brightness keys are usually F1 (dim) and F2 (brighten), located in the top row of your keyboard. Press F1 to lower the brightness. You do not need to hold any other key.

If the keys do not work, open System Preferences by clicking the Apple menu in the top-left corner and selecting "System Preferences" (or "System Settings" on newer Macs). Click Displays, then drag the "Brightness" slider to the left. The change happens right away.

Mac also offers a feature called "Night Shift" that dims the screen and shifts the color toward warmer tones in the evening. You can turn this on in the Displays settings and set a schedule for when it activates.

Lowering brightness on an external monitor

If you use a desktop computer or a laptop connected to an external monitor, the monitor itself has its own brightness control. This is separate from your computer's settings.

Look for physical buttons on the monitor — usually on the back, bottom, or side. These buttons control an on-screen menu. Press the menu button (often marked with a symbol or the word "Menu"), then use the arrow buttons to navigate to "Brightness" or "Contrast". Use the plus and minus buttons to adjust. The exact button labels vary by monitor brand, so check your monitor's manual if you cannot find them.

Some newer monitors also have brightness controls in software. Check the monitor manufacturer's website to see if they offer a control app for your model.

Why you might want to lower your brightness

Lowering your screen brightness reduces eye strain, especially in dim rooms or when working for long periods. A dimmer screen also uses less power, which extends battery life on laptops.

The ideal brightness depends on your room's lighting. In a dark room, a bright screen can cause glare and fatigue. In a bright room, you may need higher brightness to see the screen clearly. A good starting point is to set brightness so the screen is about as bright as your surroundings.

Troubleshooting brightness controls that do not work

If your brightness keys do nothing, the keyboard driver may need updating. On Windows, right-click the Start menu, select "Device Manager", find "Keyboards" in the list, right-click your keyboard, and select "Update driver". On Mac, brightness keys usually work without drivers, so if they fail, restart your computer first.

If the brightness slider in settings is grayed out or missing, your graphics driver may be outdated or missing. On Windows, go to Device Manager, find "Display adapters", right-click your graphics card, and select "Update driver". On Mac, go to the Apple menu and select "Software Update" to check for system updates.

If you have an external monitor and cannot find the brightness buttons, they may be hidden behind a panel or located on the underside. Consult your monitor's manual — most manufacturers post them online if you search the model number.

Frequently Asked Questions

Can I set my computer to automatically lower brightness at night?

Yes. Windows has a "Night light" feature in Display settings that you can schedule to turn on at sunset and off at sunrise. Mac has "Night Shift" with the same function. Both reduce blue light and dim the screen, which can help you sleep better if you use your computer in the evening.

Why is my brightness slider not moving when I drag it?

Your graphics driver may be outdated or corrupted. Update it through Device Manager on Windows or Software Update on Mac. If that does not work, restart your computer. On some older laptops, brightness controls require a specific driver that may not be installed.

Does lowering brightness actually save battery on a laptop?

Yes, but the amount varies. The screen is one of the largest power consumers on a laptop. Lowering brightness by 50 percent can extend battery life by 10 to 20 percent, depending on your screen type and other settings.

What if my monitor has no brightness buttons?

Check the back and sides carefully — buttons are sometimes small or recessed. If your monitor truly has no physical controls, look for a software control app from the manufacturer's website. Some monitors also respond to brightness commands sent from your computer through a USB or DisplayPort connection.