Device Bench

Device test · Display

Dead Pixel Test

A guided walk through six full-screen colors. Each one tells you, on screen, what a dead, stuck, or hot pixel looks like on that exact color — because every color hides one fault while it reveals another. Mark what you see as you go and the page reads your answers back as a diagnosis. Works on monitors, laptops, phones, and TVs. Wipe the screen first: most "dead pixels" are dust.

Modeready Color— Step— Shown0 of 6 Marked0 Fixernot run Flashes0 Full screenoff

In the sequence: tap or press → for the next color, ← to go back, C to mark the color clean, X to mark a defect on it, Esc to leave. Nothing advances on its own.

Or jump straight to one color:

What you found

Your own answers, recorded as you give them. The page cannot see your screen, so every verdict here is self-reported.

ScreenShownYour verdict

How this test works

An LCD or OLED pixel is three subpixels — red, green, and blue — each driven by its own transistor, and a solid full-screen color is the diagnostic because each color isolates a different failure. On pure white every subpixel should be lit, so a dead pixel appears as a sharp black dot; on pure black everything should be off, so a stuck subpixel glows as a colored point and a hot pixel as a white one; the pure red, green, and blue screens name which subpixel is at fault by the color of the dot they leave behind; and 50% gray catches partial or dim pixels that full brightness masks. The guided sequence walks all six in that order and prints the guidance for the color you are actually looking at, because the same defect is obvious on one screen and completely invisible on the next. Nothing advances by itself: you move to the next color, and you tell the page what you saw.

What the page records is your answer, not a measurement — a browser cannot look at your panel, and this one does not pretend to. It tracks which of the six screens you have displayed, which you marked clean, and which you marked as showing a defect, then reads that pattern back as an interpretation: a dot on white but not black points at a pixel that will not light, a dot on black but not white points at a subpixel stuck on, and a dot on both is usually dirt or damage on the glass rather than a pixel at all. Those readings are stated as "consistent with", because the page has one input and it is you. It also does not record where on the screen you saw a dot, so two separate defects and one confusing defect look identical to it.

The fixer is a separate, weaker claim. It flashes colors over an area you position, at a rate and for a duration you choose, on the theory that forcing many rapid state changes can free a transistor frozen in one state. The reports of that working are anecdotal, no controlled evidence backs a success rate, and nothing at all will help a genuinely dead pixel. So the fixer reports only what it did — the area, the rate you set, the number of color changes actually drawn, the time it ran, and the rate that works out to, which is lower than the setting if your browser throttled the tab. Before concluding anything, clean the screen and look from straight on: dust is soft, gray, and identical on every background, while a real defect is pixel-sharp and changes with the color behind it. If you find defects on a new display, photograph them and check the manufacturer's pixel policy while you are inside the return window.

What each color reveals

This is the table the guided sequence reads from — the prompt you see on each full-screen color is the row below it.

Screen What it isolates Dead pixel — always black Stuck pixel — wrong color Hot pixel — always white
White Every subpixel at full brightness A sharp black or dark dot. This is the screen for dead pixels. Hidden if the subpixel is stuck on; a subpixel stuck off shows as a colored dot — a dead red subpixel leaves cyan. Hidden — a hot pixel is white on a white field.
Black Every subpixel off Hidden — a dead pixel is black on a black field. A bright red, green, or blue point. This is the screen for stuck pixels. A bright white point, clearest here.
Red Red subpixels only A black dot. Yellow means green is stuck on, magenta means blue is; a black dot here with none on white means red is stuck off. A white dot.
Green Green subpixels only A black dot. Yellow means red is stuck on, cyan means blue is; a black dot here alone means green is stuck off. A white dot.
Blue Blue subpixels only A black dot. Magenta means red is stuck on, cyan means green is; a black dot here alone means blue is stuck off. A white dot.
Gray 50% Every subpixel at half drive A black dot. A dot brighter or off-hue against the field. A white dot. Dim, partly driven pixels and cloudy patches (mura) also show here and nowhere else.

Frequently asked questions

What is the difference between a dead pixel, a stuck pixel, and a hot pixel?
A dead pixel gets no power and stays black on every color, so the white screen is where you find it. A stuck pixel has one or more subpixels frozen on, so it shows the wrong color — the black screen is where it stands out, and the red, green, and blue screens tell you which subpixel is at fault. A hot pixel has all three subpixels stuck fully on, so it is a white dot that only the black screen reveals. Each screen hides one of these as surely as it reveals another, which is why the sequence walks all six.
Could that dot just be dust?
Very often, yes. Dust sits on top of the glass and looks slightly soft or gray, stays the same on every color, and moves or disappears when wiped gently with a microfiber cloth. A true pixel defect is perfectly sharp, exactly one pixel-grid in size, and changes appearance with the background color. That is why marking the same dot on both the white and the black screen points at dirt or damage rather than a pixel — a real pixel fault disappears on at least one of the two. Clean the screen before judging.
Does the stuck pixel fixer actually work?
Sometimes, by report only. The idea is that forcing a frozen transistor through thousands of rapid state changes can free it, and people do describe stuck pixels clearing after a run. That evidence is anecdotal — individual accounts rather than controlled trials — and nobody can tell you a success rate. It cannot do anything for a dead pixel, which is receiving no power at all. This page therefore reports only what it actually did: the area it flashed, the rate you chose, how many color changes it drew, and for how long. Whether anything changed is settled by running the color sequence again afterwards, not by the fixer.
Is the flashing safe, and can it damage my screen?
Rapid flashing can trigger seizures in people with photosensitive epilepsy, which is why the fixer is behind a warning you have to accept deliberately, why it defaults to 2 flashes per second — below the 3 Hz threshold usually cited as the general safe limit — and why any key press or any touch stops it instantly. The faster settings deliberately cross that threshold, so choose them only if flashing lights are safe for you and for anyone who can see the screen. For the panel itself there is no risk: solid colors and rapid color changes are ordinary operations. The one caution is OLED, where any static image left for many hours contributes to burn-in, so do not park a solid color on an OLED overnight.
How many dead pixels qualify for a warranty replacement?
It varies by manufacturer and panel class. Many follow ISO 9241-307, under which a small number of defects can be considered within spec for consumer panels, while premium or "zero bright dot" lines replace at a single bright defect. Check your manufacturer's pixel policy and run this test within the return window of any new purchase. Photograph the dot on the screen that shows it most clearly — white for a dead pixel, black for a stuck or hot one — because a claim is easier to make with an image than with a description.

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