Dead pixel test
Full-screen colors and patterns that make a dead or stuck pixel easy to see.
White
Press Esc to exit
Related tools
A dead pixel stays black whatever the screen shows; a stuck pixel keeps one color of its own. Both are easiest to spot on a plain, evenly lit background, which is what this test gives you: nine full-screen colors and four patterns, one at a time. Click, tap or press an arrow key to move on, and go fullscreen so no toolbar covers an edge of the panel. Use it when a new monitor arrives, before the return window on a phone closes, or when a spot on the display keeps catching your eye.
How to use
- Press Go fullscreen so the test covers the whole panel.
- Click, tap or press the right arrow key for the next screen; the left arrow goes back.
- On each color, look for a dot that stays black or keeps a color of its own.
- Switch to Patterns to check the lines, the checkerboard and the black-to-white ramp.
- Turn on auto-advance if you would rather watch than click.
What it handles
- Nine solid colors plus horizontal lines, vertical lines, a checkerboard and a black-to-white ramp.
- Line and checkerboard patterns are one device pixel wide, so they stay sharp on high-density screens.
- The sequence wraps, and Home and End jump to the first and last screen. Esc leaves fullscreen.
- Asks for a wake lock in fullscreen where the browser supports it, so the display does not dim mid-test.
- Auto-advance is off by default and never changes the screen more than once a second.
FAQ
What is the difference between a dead pixel and a stuck pixel?
A dead pixel gets no signal and stays black on every screen, including white. A stuck pixel still has power but holds one subpixel on, so it shows as a colored dot that never changes. Running all nine colors tells them apart: a dot you see on white but not on black is stuck; a dot you see on every color is dead.
Can this test fix a stuck pixel?
No. It shows you what the panel does, nothing more. It does not flash colors quickly to try to unstick a pixel, because that is unpleasant to watch and the result is not dependable. Use the test to find and photograph the fault, then check the warranty terms of the maker or the shop.
Does it work on a phone, a tablet or a TV?
Yes, in any modern browser. On a phone or tablet, tap the picture for the next screen and use the fullscreen button so the address bar does not hide the top rows. On a TV, open the page in the built-in browser or cast the tab; the arrow keys on a remote work like the ones on a keyboard.
Is anything uploaded, and does it work offline?
Nothing is uploaded. The colors and patterns are drawn by the page itself, so once it has loaded you can switch the connection off and finish the test. The only thing kept is your choice of screens, auto-advance and seconds per screen, stored in this browser on this device.
Why does a dot appear only on the patterns?
The lines and the checkerboard switch neighbouring pixels between black and white, which stresses a panel far more than a plain color. A pixel that is slow rather than dead shows there as a smear. Banding on the black-to-white ramp points at color depth or graphics settings, not at a faulty pixel.
Updated