What Does a Dead Pixel Look Like?

A dead pixel looks like a tiny black dot that never moves and never changes color. On a modern screen it is smaller than you might expect — on a 4K 27-inch monitor a single pixel is about 0.15 mm across, roughly the size of a grain of dust. That’s exactly why so many “dead pixels” turn out to be dust.

The telltale signs

A true dead pixel has four properties:

1. It’s black on every bright background. White, red, green, blue — the dot stays dark on all of them. Run the Dead Pixel Check to cycle through the colors.
2. It’s perfectly stationary. It stays in the exact same spot when you scroll, move windows or wipe the screen.
3. It has sharp edges. A pixel is a square element of the display grid; a defect fills that square exactly. Dust and smudges have irregular, soft outlines.
4. It disappears on black. On a black background a dead pixel is invisible, because every pixel around it is dark too.

If your dot glows red, green, blue or white on a black background, that’s not a dead pixel — it’s a stuck pixel, and it may be fixable.

Things that look like dead pixels but aren’t

Looks like	Actually is	How to tell
Black dot	Dust or a fiber	Moves or vanishes when wiped with microfiber
Black speck under the glass	Trapped debris	Slightly irregular shape, often visible at an angle
Dark smudge	Pressure mark	Larger than one pixel, soft edges
Bright dot on black	Stuck pixel	Colored, not black; only visible on dark backgrounds
Dot appears in one app only	Software artifact	Screenshot the area — if the dot is in the screenshot, it’s software

The screenshot trick is underrated: take a screenshot of the area and view it on another device or zoom in. A hardware defect can never appear in a screenshot, because the screenshot records what the computer sent to the screen, not what the panel displayed.

Seeing one clearly

Pixels are small enough that you may want help confirming what you see:

• Move closer than usual — 20–30 cm is fine for inspection.
• Use the primary color slides (red, green, blue) to check whether only one subpixel is dead: a pixel with a dead red subpixel looks fine on green and blue but shows a dark dot on red and appears slightly cyan-tinted on white.
• A drop of water on the outside of a phone screen acts as a tiny magnifier in a pinch — but a cheap loupe is better and safer.

Not sure what you’re looking for? The Dead Pixel Simulator places artificial defects on your screen so you can practice spotting them before inspecting a real panel.

Found one — now what?

Record it while you’re looking at it: the Screen Test Report lets you note the position, the background color it appeared on and the device details, then export a dated report. If the device is new, start with the retailer’s return window; otherwise check the manufacturer’s pixel policy. And if the dot is colored rather than black, try the Stuck Pixel Fixer first — you might be twenty minutes away from a clean screen.