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Dead pixel test
Start the full-screen test and look closely at the whole screen. Click or press the right arrow for the next color, and Esc to exit.
Your favorites come first on the home page and under the star at the top (in this browser).
Click, tap or press the right arrow or the spacebar for the next color; left arrow to go back. Esc to exit.
What to look for
- On black: a dot that stays lit, white or colored, is a hot pixel or a stuck pixel.
- On white: a dark dot is a pixel that isn't working (a dead pixel).
- On red, green and blue: a dot of the wrong color is a sub-pixel that is stuck on or doesn't light up.
A stuck pixel is always on: it stays red, green or blue whatever the image. A hot pixel stays bright all the time.
How to check
Clean the screen first: a speck of dust looks just like a dead pixel, but it moves when you wipe it. Then go through the colors at full screen, looking at the whole surface from close up, corners included. The pointer is hidden so it doesn't cover anything.
Keys: the right arrow, the spacebar or Enter go to the next color, the left arrow goes back, and Esc exits.
If you find one
Note its position and the color it shows up on. Whether it's covered depends on your screen's warranty terms, which differ from one maker to another.
Frequently asked questions
What's the difference between a dead and a stuck pixel?
A dead pixel doesn't work and looks dark, so you see it on white. A stuck pixel is always on in one color, so you see it on black or on the other colors.
Does this test fix stuck pixels?
No. Some programs flash colors quickly to try to free a stuck pixel; this test doesn't flash, because fast flashing images can be a problem for people with photosensitive epilepsy.
Why do I see a dot that moves?
That's dust or a mark on the glass, not a pixel.
Does it work on a phone?
Yes. If the browser doesn't allow full screen, the color fills the window: turn the phone sideways and check the edges as well.