Dead Pixel Test

How to use

1. 1Pick a test color from the grid at the top. Black exposes hot pixels, white exposes dead pixels and dust, and red, green, and blue isolate one subpixel channel at a time.
2. 2Click Go fullscreen (or press F with the stage focused) to fill your entire screen with the chosen color so the OS taskbar and browser chrome do not hide pixels at the edges.
3. 3Use the arrow keys, the Previous and Next buttons, or number keys 1 through 9 to cycle through all nine test colors. Scan the whole screen at each color, paying attention to dots that do not match the field.
4. 4If you find a stuck pixel, click Start flash (or press Space) to cycle red, green, blue, white, and black at about 4 Hz. Leave flash mode running for 10 to 30 minutes; it sometimes nudges a stuck subpixel back into normal behavior.
5. 5Toggle the pixel grid with Show pixel grid (or Z) and pick a cell size to confirm whether a suspicious dot is a single cell stuck on one color or just dust on the panel surface. Press Escape to exit fullscreen.

About this tool

Dead Pixel Test is a browser-based pixel and screen diagnostic that paints your entire viewport (or your entire screen via the Fullscreen API) with a single solid color so individual broken pixels become impossible to miss. The tool ships nine curated test colors that each isolate a different pixel failure mode. Black reveals always-on pixels (called hot or stuck-on pixels) because a single bright dot on a pure black field is unmistakable. White reveals always-off pixels (dead pixels) and dust on the panel surface. Red, green, and blue each isolate a single subpixel channel so you can spot a subpixel that is permanently stuck on or off. Cyan, magenta, and yellow check two channels at once. Gray 50% surfaces backlight bleed, panel-uniformity issues, banding, and clouding that solid primaries usually hide. The stage supports a true Fullscreen API request that hides the browser chrome, the OS taskbar, the dock, and everything else, so every physical pixel on the panel gets painted with the test color. Stuck-pixel flash mode cycles through fully saturated red, green, blue, white, and black at about 4 Hz: some monitor and panel owners use a long flash session (10 to 30 minutes) to nudge a stuck subpixel back into normal behavior. Flash mode is opt-in, runs on requestAnimationFrame so it never spins a CPU core, and shows a photosensitive epilepsy warning that auto-elevates when your operating system reports prefers-reduced-motion. A pixel-grid overlay adds a thin guide grid at 1, 2, 4, or 8 CSS pixels per cell, useful for confirming with a magnifying glass whether a suspicious dot is a real stuck pixel or just a speck of dust. Keyboard shortcuts cover everything: arrow keys cycle colors, number keys 1 through 9 jump directly to a specific color, Space toggles flash mode, F enters and exits fullscreen, H hides or shows the on-stage info card, Z toggles the pixel grid, and Escape exits fullscreen at any time. Useful for inspecting a new monitor before you accept delivery, checking a used laptop screen before you buy, validating warranty claims, finding burn-in on OLED panels, and confirming that a manufacturing defect really is a defect. Nothing runs on a server. No image is uploaded, no permission is requested, no analytics fire. The whole tool is pure CSS background colors and a small Fullscreen API call.

Free to use. Works in your browser. No signup, no login.