This dead pixel test fills your entire screen with solid colours, one after another, so faulty pixels stand out clearly against a uniform background. Cycling through black, white, red, green and blue is the standard way to reveal both dead pixels, which stay black, and stuck pixels, which are frozen on a single colour. It works on monitors, laptop panels, tablets and phones, and needs nothing but a browser in full-screen mode.
A dead pixel is a pixel that receives no power and shows as a small black dot on every colour, so it is easiest to spot on a white or bright background. A stuck pixel still receives power but is frozen on one colour channel, so it shows up as a bright red, green or blue dot, most visible on a black screen. By stepping through the full set of colours and looking closely at each one, you cover both cases. For the clearest results, clean the screen first so dust and smudges are not mistaken for pixel faults, and view the panel straight on in a dimly lit room.
Dead and stuck pixels are different problems. Stuck pixels sometimes recover on their own or can be coaxed back with rapid colour changes or gentle pressure, while a truly dead pixel is usually permanent. Knowing which one you have matters when you buy a new display, since many manufacturers only honour a warranty once the number of faulty pixels crosses a stated threshold. Running this test as soon as a monitor or laptop arrives is the best way to catch a problem inside the return window.
The test runs full screen so nothing distracts from the colour field, and you advance through the colours with a click or the arrow keys, then exit at any time with a clearly marked button or the Escape key. Everything happens locally in your browser, with no downloads and no data leaving your device, which makes it a fast and safe first check for any new or second-hand screen.
How many dead pixels does a warranty cover?
Almost no manufacturer replaces a screen for a single dead pixel, and the reason is a standard rather than a shrug. Pixel defect allowances come from the pixel fault classes originally set out in ISO 13406-2, a standard that has since been withdrawn and revised by ISO 9241-302, 303, 305 and 307:2008. The classes count three kinds of fault per million pixels: type 1 is a pixel that is always lit, type 2 is a pixel that is always dark, and type 3 is a subpixel stuck on or off.
Class I allows none of any type. Class II, which is what most consumer monitors and laptops are sold as, allows 2 type 1, 2 type 2 and 5 type 3 faults per million pixels. Class III allows 5, 15 and 50, and Class IV allows 50, 150 and 500. Turning that into real numbers: a 1920 x 1080 panel contains 2,073,600 pixels, so a Class II allowance works out at roughly four always-lit and four always-dark pixels before the panel is considered out of spec. A 3840 x 2160 panel contains 8,294,400 pixels, so the same class permits around sixteen of each.
Treat those figures as the industry reference point, not as your rights. Individual brands and retailers publish their own policies, some stricter than the class (premium monitors are sometimes sold with a zero bright pixel guarantee) and some looser, and consumer law where you live may give you a remedy the warranty does not. Count the faults with this test, note where they are, then check the policy published for your exact model before you make a claim.
How do you tell a dead pixel from dust or a scratch?
Dust and smudges are on the outside of the glass; a pixel fault is inside the panel. Three checks separate them. First, wipe the area with a dry microfibre cloth: if the dot moves or disappears, it was never a pixel. Second, tilt your head and look at the screen from an angle. Surface dirt appears to shift slightly against the image because it sits a fraction of a millimetre above it, while a faulty pixel stays locked to exactly the same point in the picture. Third, turn the screen off and look at the dark panel in good light: scratches and surface marks are still visible, but a dead pixel is not.
One more distinction worth making while the test is running. A dot that stays black on every colour, including white, is a dead pixel. A dot that is bright red, green or blue against a black field is a stuck subpixel. A dot that only shows up on a white background and never on black is far more likely to be dirt than a fault, which is why cleaning the screen before you start is the first step of the test.
How this test works
This test fills the screen with a solid colour using the Fullscreen API and a plain background colour, with no canvas, no image and no filter in between, so the colour the page requests is the colour sent to the panel. That matters: anything that processes the image could mask exactly what you are looking for. It detects nothing by itself and cannot: the judgement is yours, made with your own eyes. Note that an operating-system night light, a colour profile or HDR tone mapping still sits between the page and the panel, so switch those off before judging a display.
How to use the dead pixel test
- Clean your screen so dust and smudges are not mistaken for faults.
- Click the start button to enter full-screen colour mode.
- Click or press the arrow keys to advance through black, white, red, green and blue.
- Look closely at each colour for dots that stay dark or show the wrong colour.
- Press the exit button or the Escape key to leave full-screen mode.
Reference tables
These are server-rendered, so they are readable without running the test and quotable without running any JavaScript. Where a figure comes from a specification it is cited under the table; where it is our own judgement, the table says so.
| What it measures | What it cannot see |
|---|---|
| Show pure full-screen colours so a stuck or dead pixel stands out | Detect anything by itself: the judgement is yours, made with your eyes |
| Fill the screen with an exact colour value, unaltered by page styling | Defeat an OS night-light, colour profile or HDR tone mapping sitting between the page and the panel |
| Help you tell a dead pixel from dust: dust moves when you wipe, a dead pixel does not | Tell you whether your warranty covers what you found |
Compiled by MyGearCheck from the browser APIs each test uses. Every limit listed here is a limit of the browser, not of your hardware.
| Class | Type 1: pixel always on | Type 2: pixel always off | Type 3: faulty sub-pixels | Typically applied to |
|---|---|---|---|---|
| Class 0 | 0 | 0 | 0 | Panels sold with a zero-defect guarantee |
| Class I | 0 | 0 | 0 | Specialist and medical displays |
| Class II | 2 | 2 | 5 | Most consumer monitors, laptops and TVs |
| Class III | 5 | 15 | 50 | Lower-cost panels |
| Class IV | 50 | 150 | 500 | Rarely used for consumer displays |
ISO 9241-307 (which replaced ISO 13406-2), as summarised by display manufacturers and integrators publishing their pixel policies, read 5 August 2026. Read the class figures as faults per million pixels: a 1920 by 1080 panel has roughly 2.07 million pixels, so a Class II panel of that size may carry about four always-on or always-off pixels before it counts as faulty. Your own warranty is what decides your case, and manufacturers set their own policy on top of the standard. Check the policy for your exact model before you file a claim, and see the dead pixel warranty guide.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel gets no power and stays black on every colour, so it shows best on white. A stuck pixel is frozen on one colour and shows as a bright red, green or blue dot, best seen on black. Cycling through all the test colours reveals both types.
Can a stuck pixel be fixed?
Sometimes. Stuck pixels occasionally recover after rapid colour cycling or very gentle, careful pressure on the panel, though results are not guaranteed. A genuinely dead pixel, which receives no power, generally cannot be repaired.
How do I exit the full-screen test?
Press the Escape key or click the exit button shown on screen. Both return you to the normal page immediately, so you are never stuck in full-screen mode.
Does this work on a phone or tablet?
Yes. The test simply fills the screen with solid colours, so it works on any device with a browser. On a touchscreen, tap to advance through the colours instead of clicking.
How many dead pixels are acceptable before a screen counts as faulty?
Most consumer displays are sold to pixel fault Class II, which allows 2 always-lit pixels, 2 always-dark pixels and 5 stuck subpixels per million pixels. On a 1920 x 1080 panel that is about four of each; on a 3840 x 2160 panel about sixteen. Those classes come from ISO 13406-2, revised by ISO 9241-302, 303, 305 and 307:2008, and individual manufacturers can be stricter or looser, so check the policy for your model.
Is a dead pixel covered by warranty?
It depends on how many there are and what the manufacturer promised. A single dead pixel is usually within the allowance of a standard Class II panel and will not be replaced on its own. Count the faults with this test, note whether they are always-dark, always-lit or stuck subpixels, then compare that against the published policy for your exact model, and against your consumer rights where you live.
How do I tell a dead pixel from a speck of dust?
Wipe the spot with a dry microfibre cloth: dust moves, a pixel does not. Then look at the screen from an angle, where surface dirt appears to shift against the image while a faulty pixel stays fixed to the same point. Finally, switch the screen off: scratches and marks are still visible on a dark panel, a dead pixel is not.
Does the test find dead pixels automatically?
No, and no browser test can. It fills the screen with pure colours so a defect stands out, and the judgement is yours. Any tool claiming automatic detection cannot see your screen.
Does a night light or colour profile affect the result?
Yes. A night light, a colour profile or HDR tone mapping sits between the page and the panel, so the colour you see may not be the value the page requested. Switch those off before judging a display.
Can I use this on a TV?
Yes, if you can open a browser on it or cast the tab. A TV is worth checking on solid black in a dark room, which is where both stuck pixels and panel uniformity show up.
Should I be careful with the flashing colours?
Yes. The colours only change when you ask them to, never automatically, and if you are sensitive to flashing that is deliberate. Move through them at your own pace.
Guides for this test
The test shows you what is happening. These explain what to do about it.
More hardware tests
The closest tests to this one are the rest of the display group. Working through a whole machine instead? The full check runs everything in order and ends in one report.
Everything else in the suite: