Dead pixel test
Press Start and the whole screen turns one solid color. Tap or press an arrow key to move through black, white, red, green, blue and gray, and look for dots that do not match. Press Esc to leave.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Clean the screen and set the brightness to a high level.
- Press Start the test. The page asks for fullscreen where the browser allows it.
- Tap, press Space or use the arrow keys to move through the six colors. Look at the screen from close up, section by section.
- Press Esc or Exit when you are done.
What to look for
- A dot that stays black on the white, red, green and blue screens is a dead pixel.
- A dot that stays bright on the black screen is a stuck pixel; its color tells you which sub-pixel is stuck.
- Bright edges or patches on the black screen are backlight bleed, and blotches on gray show uneven brightness.
Worked example
On a 1920 × 1080 screen there are 2 073 600 pixels. Each one has three sub-pixels (red, green and blue), about 6.2 million in all. If one bright dot on the black screen turns out to be green only, that single green sub-pixel is stuck on, while the dot looks white-ish on a white screen because the other two are still working.
Tips
- Dust is not a pixel. If a dot can be wiped away with a soft cloth, it was dust.
- Check the warranty rules. Makers differ in how many faulty pixels they accept, so look up your model’s policy before returning a screen.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel stays black on every color. A stuck pixel stays lit in one color, for example always red or green. Stuck pixels can sometimes be fixed; dead ones usually cannot.
Which color shows which problem?
Black shows bright stuck pixels and light leaking from the backlight. White shows dead pixels. Red, green and blue show single sub-pixels that fail. Gray shows uneven brightness and patchy areas.
How do I switch colors and exit?
Tap or click the screen, or press Space or the right or down arrow, to go to the next color. The left and up arrows go back. Esc, or the Exit button in the corner, ends the test.
Why does it not go fullscreen on my phone?
Some mobile browsers, notably on iPhone, do not let a page enter fullscreen. The test then fills the browser window instead, which is enough for a check; the browser's own bars may still show.
Is anything recorded?
No. The page only paints solid colors. Nothing is captured or sent.