What is the difference between a dead pixel and a stuck pixel?

A dead pixel gets no power at all — its transistor is open-circuit, so it stays black no matter what the screen is told to display. You see it as a dark dot on a white field and not at all on black. A stuck pixel is the opposite problem: one or more of its three subpixels is frozen at full brightness, so the pixel glows red, green, blue, or white on a black field. Stuck pixels sometimes recover. Dead ones do not.

Why does the test need so many colours?

Because a single stuck subpixel is invisible against its own primary. A red subpixel frozen on disappears completely on a red field and stands out instantly on green or blue. Black catches everything that lights up when it should be off, white catches everything that stays dark, and the secondaries — yellow, cyan, magenta — catch subpixels that are dim rather than fully dead. Five colours is the usual minimum; this test uses nine.

Can a stuck pixel be fixed?

Occasionally. The flash mode on this page drives the cell between full brightness and black about five times a second, which sometimes unsticks a transistor that is holding a fixed charge. Give it ten to twenty minutes before deciding it failed. Gentle pressure with a soft cloth over the exact spot, applied while the flashing runs, is the other method people report success with — but press lightly, because too much force can damage the layers underneath permanently. A genuinely dead pixel will never come back by either route.

How many dead pixels before I can return the monitor?

That depends on the fault class the panel was sold under, and almost every consumer monitor and laptop is Class II. On a 1920 × 1080 panel, Class II allows 4 permanently lit pixels, 4 permanently dark pixels and 10 stuck subpixels before the panel is out of spec. The allowance table on this page does that arithmetic for your actual resolution. Check the manufacturer's own policy too — Dell, Apple and LG all publish stricter terms than the standard requires for some product lines.

I see a mark on every single colour. Is that a dead pixel?

Almost certainly not. A pixel fault changes with the field colour: it is either dark on light or bright on dark. A mark that looks identical on black, white, red and green is on top of the panel, not inside it — dust, a fingerprint, a dried water spot, or a scratch in the anti-glare coating. Wipe the screen and run the test again before you file a warranty claim.

Does this work on a phone, tablet or TV?

Yes. It is a web page filling the viewport with a solid colour, so anything with a browser works, including Android TV and most smart-TV browsers. On a phone, tap to advance and use the back gesture or Esc on a keyboard to exit. On OLED panels be aware the test is also a decent way to spot burn-in: a uniform grey or white field makes retained images from a status bar or news ticker very obvious.

Is the test safe to leave running?

The colour cycle is static and harmless. The flash mode alternates between bright and dark several times a second, so skip it if you are photosensitive or prone to migraines — and do not leave a static bright field on an OLED screen for hours, since that is exactly the condition that causes burn-in. Nothing is uploaded and no permissions are requested; the page only reads your screen dimensions to compute the fault allowance.

Why does my reported resolution look smaller than I expect?

The first number is in CSS pixels, which is what the browser works in. On a phone or a HiDPI laptop the panel packs two or three physical pixels into each CSS pixel, so the real count is the CSS size multiplied by the device pixel ratio. Both numbers are shown, along with the subpixel total — three per pixel on a standard RGB stripe panel, which is the figure the stuck-subpixel allowance applies to.

Dead Pixel Test — Check Any Screen for Dead Pixels

Wipe the screen with a dry cloth first — dust is the most common false alarm. Then go full screen and step through the colours.

Click to advance, click the left third to go back, Esc to exit. The flash mode strobes a few times a second — skip it if you are photosensitive.

Or jump straight to one colour

Your screen

CSS resolution

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Physical pixels

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Pixel ratio

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Pixels to inspect

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Subpixels

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Megapixels

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Found a dot? Tick what you saw

It lit up on the black field It stayed dark on the white field It looked the same on every colour, not just one or two

How many faults your warranty allows

ISO 9241-307 fault class

Bright dots

Dark dots

Stuck subpixels

Combined limit

Counts are for your detected resolution. Manufacturers often publish their own policy on top of the standard, so check the warranty page for your exact model before claiming.

A dead pixel hides against most of what is on your screen, which is why you only ever notice it on a solid colour. This test fills the whole display with one flat colour at a time — red, green, blue, black, white and the three secondaries — so a pixel that is stuck on, stuck off, or showing the wrong tint has nowhere to blend in. Tick what you saw and the page tells you which fault you are looking at, whether flashing is worth trying, and how many faults your panel's warranty class actually allows.

How it works

1
Clean the screen first Wipe the display with a dry microfibre cloth before you start. A speck of dust looks exactly like a dead pixel on a white field, and it is the single most common false alarm.
2
Run the full-screen cycle Press 'Start full-screen test'. Click anywhere or press the right arrow to move to the next colour, and the left third of the screen to go back. Hold your face about 40 cm from the panel and sweep your eyes across it rather than staring at the centre.
3
Name what you found Press Esc to come back, then tick the boxes for where the dot was visible. The verdict tells you whether it is a dead pixel, a bright one, a stuck subpixel, or just dirt — and the allowance table shows how many of them your panel is permitted to have.

Your data stays private

All processing happens entirely in your browser. No files, text, or data are ever sent to our servers. You can disconnect from the internet and this tool will still work.

Frequently asked questions

What is the difference between a dead pixel and a stuck pixel?: A dead pixel gets no power at all — its transistor is open-circuit, so it stays black no matter what the screen is told to display. You see it as a dark dot on a white field and not at all on black. A stuck pixel is the opposite problem: one or more of its three subpixels is frozen at full brightness, so the pixel glows red, green, blue, or white on a black field. Stuck pixels sometimes recover. Dead ones do not.
Why does the test need so many colours?: Because a single stuck subpixel is invisible against its own primary. A red subpixel frozen on disappears completely on a red field and stands out instantly on green or blue. Black catches everything that lights up when it should be off, white catches everything that stays dark, and the secondaries — yellow, cyan, magenta — catch subpixels that are dim rather than fully dead. Five colours is the usual minimum; this test uses nine.
Can a stuck pixel be fixed?: Occasionally. The flash mode on this page drives the cell between full brightness and black about five times a second, which sometimes unsticks a transistor that is holding a fixed charge. Give it ten to twenty minutes before deciding it failed. Gentle pressure with a soft cloth over the exact spot, applied while the flashing runs, is the other method people report success with — but press lightly, because too much force can damage the layers underneath permanently. A genuinely dead pixel will never come back by either route.
How many dead pixels before I can return the monitor?: That depends on the fault class the panel was sold under, and almost every consumer monitor and laptop is Class II. On a 1920 × 1080 panel, Class II allows 4 permanently lit pixels, 4 permanently dark pixels and 10 stuck subpixels before the panel is out of spec. The allowance table on this page does that arithmetic for your actual resolution. Check the manufacturer's own policy too — Dell, Apple and LG all publish stricter terms than the standard requires for some product lines.
I see a mark on every single colour. Is that a dead pixel?: Almost certainly not. A pixel fault changes with the field colour: it is either dark on light or bright on dark. A mark that looks identical on black, white, red and green is on top of the panel, not inside it — dust, a fingerprint, a dried water spot, or a scratch in the anti-glare coating. Wipe the screen and run the test again before you file a warranty claim.
Does this work on a phone, tablet or TV?: Yes. It is a web page filling the viewport with a solid colour, so anything with a browser works, including Android TV and most smart-TV browsers. On a phone, tap to advance and use the back gesture or Esc on a keyboard to exit. On OLED panels be aware the test is also a decent way to spot burn-in: a uniform grey or white field makes retained images from a status bar or news ticker very obvious.
Is the test safe to leave running?: The colour cycle is static and harmless. The flash mode alternates between bright and dark several times a second, so skip it if you are photosensitive or prone to migraines — and do not leave a static bright field on an OLED screen for hours, since that is exactly the condition that causes burn-in. Nothing is uploaded and no permissions are requested; the page only reads your screen dimensions to compute the fault allowance.
Why does my reported resolution look smaller than I expect?: The first number is in CSS pixels, which is what the browser works in. On a phone or a HiDPI laptop the panel packs two or three physical pixels into each CSS pixel, so the real count is the CSS size multiplied by the device pixel ratio. Both numbers are shown, along with the subpixel total — three per pixel on a standard RGB stripe panel, which is the figure the stuck-subpixel allowance applies to.

From the blog

How to Find a Dead Pixel (and Tell It From Dust) Run a full-screen colour check, work out whether the dot is dead, stuck or dirt, and find out how many faults your warranty actually covers. Read the post →