Dead / Stuck Pixel Test
Find dead and stuck pixels with fullscreen colours — and tell the two apart.
Black. A bright dot here is a stuck pixel.
After cycling every colour, what did you see?
How this test works
The test fills the screen with black, white, the three primaries, the three secondaries and mid-grey, one at a time. A dark dot that persists on every fill is a dead pixel; a dot that holds one colour and shows up against black is stuck; anything visible on white but gone on black is on the surface of the glass rather than in the panel. Before that, it measures coverage: it multiplies the surface size by the device pixel ratio and compares the result with what the display reports, because browser zoom, OS scaling and a window on the wrong monitor all leave part of the panel untested while the test still looks like it passed.
What the results mean
- Dead pixel
- Dark on white and on every colour. The pixel receives no signal. Dead pixels do not recover, and no software routine has ever fixed one.
- Stuck pixel
- Holds one colour — visible as a bright dot on black. The subpixel is still being driven but is not changing. Some recover on their own, and a rapid colour-cycling routine recovers some of the rest.
- Pixels painted
- Device pixels the pattern is actually filling, against what the display reports having. If these do not match, part of your screen is not being tested — reset zoom to 100% and run it fullscreen on the display you care about.
- Mura and clouding
- Uneven patches on the grey and black fills rather than single dots. That is backlight unevenness, common on large IPS panels and judged by degree rather than pass or fail.
Common problems and fixes
- The spot only appears on white
- It is dust, a fingerprint or a fleck of grease on the outside of the panel. Wipe with a dry microfibre cloth. A pixel fault appears on black too.
- The colours do not fill my whole screen
- Reset browser zoom to 100%, press the fullscreen button, and drag the window fully onto the display you want to test. The coverage figure in the result tells you when it is right.
- I see a dark patch rather than a dot
- A patch is backlight bleed or clouding, not a pixel fault. It is most visible on black in a dark room and is a manufacturing tolerance question, which is a different test.
- The dot moved when I scrolled
- Then it is in the image, not the panel — a compression artefact or a mark on a photo. A panel fault stays in exactly the same physical spot no matter what is displayed.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel gets no signal and stays black on every colour, including white. A stuck pixel is still being driven but holds one value, so it shows as a coloured or bright dot and is most obvious against black. The distinction decides what to do next: stuck pixels sometimes recover, on their own or with a flashing routine, and dead ones never do.
Can a dead pixel be fixed?
No. Every product and routine sold as a dead-pixel fix is aimed at stuck pixels, where rapid colour cycling can free a subpixel that has settled. A pixel receiving no signal has a broken connection inside the panel, and nothing on the outside changes that.
How many dead pixels before a warranty replacement?
It depends on the manufacturer and the panel grade, and the policy is usually published. Thresholds of several pixels are common, but many makers treat a single bright pixel, or one anywhere near the centre of the screen, differently from a dark one at the edge. Photograph the fault on both a white and a black fill before you contact support — a claim with both images is handled faster.
Does this test work on a phone or a TV?
Yes on a phone or tablet — open this page, go fullscreen and cycle the colours. On a TV, load it in the built-in browser or cast a fullscreen browser window; the coverage figure will tell you whether the picture is really addressing the panel one to one or being scaled on the way in.