How to adjust monitor brightness on a laptop or desktop screen

Brightness is controlled in one of two places, and which one you need depends on the screen in front of you.

• Laptop screen: the brightness keys on the keyboard, or the display settings in Windows or macOS.
• External monitor on a desktop: the monitor's own on-screen menu, reached with the buttons or joystick on the bezel or round the back. The Windows or macOS slider only moves an external monitor if it supports DDC/CI and that feature is switched on.
• External monitor plugged into a laptop: usually the monitor's own menu, for the same reason.

Whichever route you use, the target is the same: a plain white page should look roughly like a sheet of paper in the same room, not like a lightbox. White text on a dark background should be comfortable to read without squinting, and a dim room shouldn't leave the screen glowing at you.

Nothing here needs a tool, a download or a calibration device. Have these to hand and the whole job takes a couple of minutes.

On a laptop the brightness control is part of the operating system, so there are usually several routes to the same setting.

• Windows 11: Settings > System > Display, then the Brightness slider.
• Windows 11 quick route: the Quick Settings panel — click the volume or network icon in the taskbar and use the brightness tile.
• Windows 10: Settings > System > Display, in the Brightness and colour section.
• macOS: Control Centre > Display slider, or System Settings > Displays > Brightness. The top-row brightness keys work unless they've been remapped to standard function keys, in which case hold Fn.
• Night light (Windows) and Night Shift (macOS) warm the colours after dark. Neither changes brightness, so don't expect them to fix a screen that's too bright at night.

Nearly every standalone monitor has an on-screen display: a menu drawn by the monitor itself, not by the computer. It doesn't care what operating system you use.

• Press the menu button or nudge the joystick. The control nearest the power button is usually Menu or OK.
• Look under Picture, Image or Brightness/Contrast for the Brightness entry.
• Some monitors split the control, with Brightness on one page and Backlight, Black level or Gamma elsewhere.
• While you're in there, find the DDC/CI option — often under Setup, OSD, Other or System — and switch it on if you want the computer's slider to work.
• Press Menu or Exit to save. Most monitors save as you go, but a few need an explicit OK.

A slider that won't move, or moves without changing the picture, almost always comes down to one of these:

• DDC/CI is off. External monitors only accept brightness commands when the feature is enabled in the monitor's own menu.
• You're on a desktop PC. Windows brightness controls are aimed at laptop panels; on many desktops the slider is missing entirely and the monitor menu is the only route.
• HDR is switched on. Windows can hold the output at a fixed level in HDR and offers a separate SDR content brightness slider in its HDR settings. Some monitors also lock brightness in HDR mode.
• The picture mode is fixed. HDR, Game and Cinema presets sometimes pin the backlight.
• Something sits between the two. Docks, KVM switches and adapters don't always pass brightness commands through.
• The driver isn't playing ball. On Windows, updating or reinstalling the display driver often brings the slider back.
• It's a Mac with a third-party screen. Some monitors need a DDC/CI utility before macOS will move the backlight at all.

If the screen looks washed out rather than too dim, the culprit is more likely the picture mode or the black level setting than brightness. Black level (sometimes called HDMI black level or gamma) controls how dark the darkest parts of the image appear; set it wrong and blacks turn grey even with the backlight at a sensible level. A quick check is a photo with deep shadows: if the shadow areas look milky at a comfortable brightness, adjust black level or gamma rather than pushing the backlight down further.

There is no single correct number that works everywhere, because the right level depends on the light around you. In a dim home office, most people end up well below the halfway mark; in a bright, south-facing room, closer to the top of the range is normal.

The paper test is the most reliable one you can do without equipment. Take a sheet of white paper, hold it beside a white page on screen under your normal room lighting, and adjust until the two look similar. Your eyes adapt within seconds, so compare back and forth a few times rather than trusting a single glance.

For photo and video work, consistency matters more than perfection. Pick a level that suits your room, note where it sits, and use the same setting each session — otherwise your images will look different every time you edit. If you regularly match images to prints, set brightness and contrast once in controlled lighting and leave them alone, rather than nudging the backlight when a file looks dull.

• Judging in the wrong light. Setting brightness in a dark room and then working in daylight means you'll redo it every day.
• Leaving it at maximum all the time. A backlight at full power uses more energy and produces more heat, and on OLED screens sustained high brightness adds to burn-in risk.
• Dimming with software instead of the monitor. Tools that darken the image rather than the backlight reduce contrast and can crush shadow detail. The monitor's own control is the better option where it exists.
• Mistaking night modes for brightness. Night light and Night Shift change colour temperature, not output.
• Chasing a number. Brightness guidance taken from someone else's room and someone else's panel rarely suits yours; trust the paper comparison and your own comfort.