Dead Pixel Test
Fill your screen with solid white, black, red, green, blue and gray to spot dead or stuck pixels — plus a flashing fixer that may revive stuck ones.
Processed entirely in your browser — nothing you enter here is ever uploaded.
Result
About this tool
Checking a brand-new monitor before the return window closes, inspecting a second-hand phone, or hunting a suspicious dot on your laptop? A dead pixel test takes minutes: fill the screen with a series of solid colors and look closely — a healthy panel shows a perfectly uniform field, while defective pixels stand out as dots that refuse to match their surroundings.
Each color exposes a different defect. On white, dead pixels appear as dark specks (and so does dust — wipe the screen first). On black, stuck pixels glow as tiny colored or white points, and LCD backlight bleed becomes visible in a dark room. Red, green and blue light up one subpixel channel at a time, so you can tell exactly which subpixel is stuck or gone. Click or use the arrow keys to cycle colors, and press Esc to finish.
The second mode is a stuck-pixel fixer: a small draggable square rapidly flashes red, green, blue, white and black — one color per screen refresh. A stuck pixel is a subpixel frozen in one state, and forcing fast state changes for 10–15 minutes sometimes unsticks it. Results are genuinely mixed, so treat it as worth trying, not guaranteed. A dead pixel — one that stays black on every color — gets no power at all, and no software can fix that; check your manufacturer's pixel policy instead, because many panels qualify for warranty replacement.
Everything runs locally with standard browser APIs: the Fullscreen API paints the test panels and requestAnimationFrame drives the fixer. Nothing is uploaded, nothing is installed, and the test works the same on monitors, laptops, phones and tablets.
Example. Choosing the red swatch paints the full-screen overlay #ff0000.
Limit. The flasher cycles five colors and never reads pixels back, so it cannot report a dead-pixel coordinate.