Device tests · Display
Dead Pixel Test
Use this dead pixel test to inspect your monitor or phone screen against nine solid full-screen colours. Persistent dots are easier to spot when the surrounding display is a uniform colour.
The test does not detect defects automatically. You decide what you see, and no screen information or result is saved or uploaded.
- 9 solid colours
- Fullscreen inspection
- No automatic diagnosis
Inspect your screen, one colour at a time
- Clean the screen first.
- Start the test.
- Look closely at each solid colour.
- Check for dots that stay black, white or another incorrect colour.
- Move through every colour.
- Finish when complete.
No automatic diagnosis is performed. You inspect the colours visually, and nothing about your screen is saved or uploaded.
Browser-reported display information
- Screen resolution
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- Viewport size
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- Device pixel ratio
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- Colour depth
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These are values reported by your browser. They are not physical panel dimensions or a measurement of pixel density.
Your result
What your result means
A suspicious dot that stays in exactly the same place across several backgrounds may be a pixel or subpixel issue. Different defects can look dark, bright or fixed to one colour.
One visual pass cannot identify the exact hardware fault. Clean the screen and repeat the sequence before drawing a conclusion, because dust, dirt, reflections and surface damage can look similar.
- Black and dark backgrounds make persistently bright pixels easier to notice.
- White and bright backgrounds make persistently dark pixels easier to notice.
- Red, green and blue help reveal a subpixel that does not change with the rest of the image.
- Cyan, magenta, yellow and gray provide additional contrast for subtle colour or brightness differences.
Procedure
How the test works
- 01
Clean the display
Turn the screen off if needed and follow the manufacturer's cleaning guidance. Do not press hard on the panel.
- 02
Start fullscreen
Press “Start Dead Pixel Test”. If fullscreen is declined, the same colour surface fills the browser window.
- 03
Inspect each colour
Look closely across the whole surface. Use Previous and Next, or the left and right arrow keys, to change colour deliberately.
- 04
Compare one location
If a dot looks wrong, note its position and inspect that same position against several colours.
- 05
Finish safely
Press Finish test or use Escape to leave browser fullscreen. There is no rapid or automatic colour cycling.
Methodology
How Testpartout measures this
This is a visual inspection method: the page supplies controlled solid backgrounds, while you observe the display.
What the implementation does
- The test presents black, white, red, green, blue, gray, cyan, magenta and yellow as uniform browser-rendered backgrounds.
- Colours change only after a deliberate button press or left/right arrow key action; there is no flashing sequence.
- The Fullscreen API is requested from the start button. If unavailable or rejected, a fixed surface fills the current browser window.
- The result question records only your own observation and does not calculate a score or diagnosis.
- Screen resolution, viewport, device pixel ratio and colour depth are read from standard browser properties and labelled as browser-reported values.
Limits of a browser measurement
- A browser cannot identify whether a suspicious dot is a dead pixel, stuck subpixel, panel damage, contamination or another hardware issue.
- Browser-rendered colours can be affected by display profiles, operating-system processing, brightness settings and the panel itself.
- The reported screen resolution may use CSS pixels and scaling; it is not necessarily the panel's native physical resolution.
- This test does not measure physical pixel density, response time, colour accuracy, uniformity or refresh rate.
- A visual inspection cannot guarantee that every defect is found.
Privacy
What happens to your data
This section describes the behaviour of the code on this page, not an intention.
- The colour test runs entirely in your browser and does not need camera, microphone or file access.
- Your visual answer is kept only in the current page state and is not saved or uploaded.
- No screenshot, display image or screen identifier is captured.
- Only consent-controlled test interaction events may be sent through the site's existing analytics settings.
Troubleshooting
If the test does not behave as expected
Fullscreen did not open
Allow fullscreen if your browser asks, or use the browser's own fullscreen command. The in-window colour surface still works.
Controls disappeared
Tap or click anywhere on the colour surface to reveal them. On desktop, the left and right arrow keys also change colours.
A mark appears on every colour
Clean the display according to its maker's guidance and inspect the same location again. Do not apply pressure to the panel.
The colour is not perfectly uniform
Brightness uniformity, viewing angle, reflections and display processing can create broader patches that are not single-pixel defects.
Escape ended the test
That is normal browser fullscreen behaviour. The page returns to the result question without trapping the keyboard.
A phone browser hides part of the screen
Browser bars may remain visible when fullscreen is restricted. Rotate the device or use the browser's fullscreen option if available.
Factors
Pixel defects and common lookalikes
These terms describe different visual symptoms, but this browser test cannot confirm their precise cause.
Dead pixel
A dead pixel often remains dark because it is not producing visible light. Its appearance can vary with panel technology and the underlying fault.
Stuck pixel
A stuck pixel or subpixel may remain red, green, blue or another colour instead of following the image. A solid-colour sequence makes that mismatch easier to compare.
Hot or bright pixel
A hot or bright pixel remains visibly lit, so it is usually easiest to notice against black or another dark background.
Subpixel issue
Each displayed pixel is commonly formed from colour subpixels. If one responds differently, the dot may look tinted on some backgrounds but normal on others.
Dust or dirt
Surface contamination can resemble a dark pixel. It may change appearance with the viewing angle and should be ruled out with safe cleaning.
Surface damage
Scratches, pressure marks and damaged coatings can cover more than one pixel or change with reflections. Do not press on the panel to test them.
Backlight non-uniformity
Larger bright or dark patches are different from a single pixel. They may be more visible on gray or black and can vary with viewing angle.
Image retention
A faint shape left from earlier content is broader than a single pixel. Its behaviour and remedies depend on the display technology; follow the manufacturer's advice.
FAQ
Frequently asked questions
- How do I check my monitor for dead pixels?
- Clean the screen, start the test and inspect every area against black, white, red, green, blue, gray, cyan, magenta and yellow. A suspicious dot that remains fixed in the same location should be checked again on several colours.
- What is the difference between a dead pixel and a stuck pixel?
- A dead pixel often stays dark, while a stuck pixel or subpixel may remain one colour. Appearance varies, and this visual test cannot automatically determine the exact fault.
- Why does the test use several solid colours?
- Different backgrounds create different contrast. Dark pixels stand out on bright colours, bright pixels on black, and colour subpixel issues can become clearer on red, green, blue and their combinations.
- What is a hot or bright pixel?
- It is a pixel that remains visibly bright when it should be dark. A black test background usually gives it the strongest contrast.
- Can dust look like a dead pixel?
- Yes. Dust, dirt, reflections and surface damage can resemble pixel defects. Clean the display safely and inspect the same location again before deciding.
- Can this dead pixel test repair stuck pixels?
- No. This page is an inspection tool and does not promise or attempt a repair. Follow the display maker's support guidance if you find a persistent issue.
- Is the colour sequence safe from rapid flashing?
- The page does not cycle colours automatically. A colour changes only when you press Previous or Next or use an arrow key.
- Does the test save information about my screen?
- No. Screen details and your result are displayed locally for the current page session; no screenshot, screen identifier or result is saved or uploaded.
Found an issue with this test? Report it.