Full-Screen Color & Dead Pixel Test Tool
Display a solid white, black, red, green, or blue screen — or any custom color — to check a monitor, laptop, or phone screen for dead pixels, stuck pixels, backlight bleed, and uneven color. Works entirely in your browser, nothing to install.
Frequently asked questions
What is a dead pixel?
A dead pixel is a pixel on a screen that stays permanently black (or fails to light up at all) no matter what color the rest of the display is showing. It happens when a pixel's transistor fails and stops receiving power entirely. Dead pixels are usually easiest to spot against a bright, solid background like white or a bright color, since a single black dot stands out clearly.
How do I test for a dead pixel?
Use the Fullscreen button above and cycle through white, black, red, green, and blue (or use "Start Cycle" to do this automatically). Look closely at the entire screen against each color — a dead pixel will show up as a tiny dot that never changes, no matter which color is displayed behind it. It helps to dim the room and look at the screen from a normal viewing distance, then again up close.
What's the difference between a dead pixel and a stuck pixel?
A dead pixel is unpowered and shows black on every background. A stuck pixel is still receiving power but is stuck displaying one color (often red, green, or blue) regardless of what the screen is supposed to show — so it stands out as a colored dot rather than a black one. Stuck pixels are sometimes fixable by gently massaging the area or using pixel-flashing techniques; dead pixels generally aren't, since the pixel itself has no power.
How do I use this to test a used monitor, laptop, or phone before buying?
Before buying a second-hand screen, open this tool on the device you're checking (or connect the monitor to a laptop you control) and go fullscreen. Cycle through all five colors and inspect every corner and edge of the panel, since dead and stuck pixels are often clustered near the borders. Also watch for backlight bleed on the black screen (light leaking in from the edges) and any color that looks uneven or has a visible tint compared to the rest of the panel — both are common signs of wear on used displays.
What else can I use a full-screen color tool for?
Beyond pixel testing, a solid full-screen color is useful for: turning your screen into a soft ambient light source (a warm or dim color works well as a bedside light or bias lighting behind a TV); a plain white or black background for video calls, presentations, or focus/productivity sessions; and rough color and brightness calibration checks on projectors or external TVs before fine-tuning with dedicated calibration hardware.
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