How this test works
The page displays #000000 as a single CSS background. Use the empty field to inspect LCD backlight bleed or IPS glow, and look for dots that remain bright against black. Reflected light can make dust and fingerprints visible too. This is a visual check: the page cannot see those marks or measure how much light the panel emits. The field does not flash or cycle; it holds the one color until you exit.
Press Go full-screen black to request browser fullscreen. If the browser refuses or does not support it, a black overlay fills the page's viewport instead, so browser controls may remain visible. Press Esc, use the browser's fullscreen-exit gesture, or tap the ✕ to return. If the ✕ has faded, tap the field or move the pointer to show it again. The readout gives the color and hex value, browser-reported screen and viewport dimensions in CSS pixels, and fullscreen state. These values are read locally; nothing leaves your device.
LCDs block backlight to show black, so some light can remain visible. OLED pixels can switch off for black, so an all-black field cannot show how evenly the panel displays near-black grays. Room reflections, viewing angle, brightness, and display settings affect what you see. A bright spot or cloudy patch is a reason to compare other fields, not enough on its own to diagnose a fault or decide a warranty claim. To document a bright dot for a claim, see the guide to dead pixel policies and ISO 9241-307.
Frequently asked questions
What is a black screen test for?
A black field gives you a background for checking LCD backlight bleed, corner glow, and bright dots that may indicate a stuck pixel or subpixel. It can also make dust and fingerprints easier to see. Inspect the field yourself; the page does not detect or label defects.
Why isn't the black screen perfectly black on my monitor?
An LCD forms black by blocking its backlight, and some light can still get through. How much you see depends on the panel, its settings, your viewing angle, and the room's reflections. Some displays dim the backlight for a black image. OLED pixels emit their own light and can switch off for black, so an OLED may look much darker in the same room.
Will this test find dead pixels?
Black is useful for spotting pixels or subpixels that stay bright, not those that stay dark. A fully dark pixel blends into this field. Check the white screen or step through the dead pixel test's color sequence as well; compare the same spot on each background before drawing a conclusion.
Can I use the black screen while cleaning my monitor?
Use it to locate dust and smudges before cleaning, then switch the display off and follow the manufacturer's cleaning instructions. Use a microfiber cloth, dry or only slightly damp where permitted, and avoid solvents. The black overlay is not a cleaning lock: taps and key presses can still affect the page or device.
Does showing black save power or help the battery?
An OLED generally uses less display power for black than for a bright image because its pixels can stop emitting light. On an LCD, the backlight usually accounts for much of the power use, so a black image may make little difference unless the display dims it. This page holds a static color, but it does not measure power use or battery savings.
