Use comfortable display brightness and a stable viewing position. Mark a repeatable location and compare white, black, red, green and blue before recording the symptom. The mark describes where you looked, not a verified hardware fault.
Screen test for dead and stuck pixels
Run a screen test to compare a repeatable mark across white, black and primary-colour fields. Record what stays in the same position before choosing a support or maintenance step.
Also known as: screen test, monitor test, display test, lcd test, tester lcd, desktop monitor test, dead pixel test, stuck pixel test. Free, online, and no download required.
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Check one location
- Keep the same display, comfortable actual brightness, room light, browser zoom, system scaling and viewing position. Select Clear marks, then Reset run before a fresh comparison.
- Enter fullscreen with the control below so the colour field covers the visible display. If the browser refuses, record the area the embedded pattern covers instead of treating hidden edges as inspected.
- Compare white, black, red, green and blue at one fixed location. A dark point on light fields and a bright or coloured point on black need separate notes.
- Click the suspect position to mark its coordinates, then move the pointer away and check the same position on each field. Marks are shown only on the colour field where you placed them; record the other colours separately rather than assuming a hidden mark disappeared from the physical panel.
- Exit fullscreen to read Visited and Marked locations. Finish and read result summarizes visited fields and marks you added, not an automatic pixel scan. No recorded marks does not prove a fault-free panel.
- Save notes with the date, display model, browser/version, conditions, location and visible colours. Use Clear marks to delete stored markers; Reset run does not delete saved marks. Repeat with one condition changed and keep unknowns explicit.
Review the room and brightness prompt, then enter fullscreen.
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What the screen test for dead and stuck pixels checks
| Check | How it is measured | Fails when |
|---|---|---|
| Pattern coverage | Nine solid and structured patterns are available in fullscreen. | Fullscreen is refused and the embedded pattern cannot fill the viewport. |
| Defect marks | Pointer positions are normalized to the active pattern bounds. | A mark cannot be restored or cleared. |
| Navigation | Arrow keys change patterns and F toggles fullscreen. | The active browser reserves a required key. |
If something failed
Use the existing fullscreen control and check the exposed area. Browser bars or system scaling can change what is visible. Record an incomplete view rather than treating a hidden edge as a passed check.
It cannot prove the electrical cause of a point, repair a failed pixel or establish warranty coverage. It also cannot calibrate luminance or colour accuracy. The screen test shows controlled fields and local marks; follow the monitor check guide for a wider visual comparison.
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How to read the result
Dead pixel test: reading the colour sweep
Check one location. A dead pixel test provides controlled fields for visual inspection, not an electrical diagnosis of the panel. Look for a point that stays at the same screen position while the colour changes, then distinguish it from a cursor, reflection or visible surface mark.
Does the point remain dark on white and the primary colours? Record that pattern as a possible dark-pixel symptom. Does a point remain bright on black? Record its colour and position separately. The stuck pixel test cannot inspect which subpixel or circuit is responsible, so keep the observation separate from a repair conclusion.
Use the dead pixel vs stuck pixel guide before changing anything. For a laptop point, follow the laptop repair guide; a whole row or column belongs in the line diagnosis guide. Compare the same brightness, zoom and viewing position across fields. Do not press the panel.
Check for dust, residue or reflections using the maker's cleaning guidance and compare the same spot in another app or the display's own menu. Browser colour fields cannot inspect panel electronics or prove warranty eligibility. Review the model's policy with your notes before considering the stuck pixel fixer; its flashing colours carry a photosensitivity warning and offer no guaranteed repair.
How the screen test works
Enter fullscreen with the on-page control, then use the pattern buttons or arrow keys to switch between the nine solid and structured fields. F toggles fullscreen and Escape exits it through the browser.
Click a suspect location to place a mark. The page stores normalized coordinates locally, tagged with the active colour field, so the mark can be compared after the pattern area changes size. Marked locations counts saved markers across all fields; markers are visible only on their original field. A mark records your observation; the page does not detect a faulty pixel for you.
What the result can establish
Use comfortable display brightness and a stable viewing position. Mark a repeatable location and compare white, black, red, green and blue before recording the symptom. The mark describes where you looked, not a verified hardware fault.
Visited counts distinct patterns used in this run, not verified physical pixels. Fewer than three visited patterns leaves the check inconclusive; a newly marked location prompts review. A result with no marks means none were recorded during this run, not that every physical pixel passed inspection.
Clear marks removes saved markers from this browser. Reset run clears the timer and visited-pattern count but leaves saved marks visible. Stored or restored markers are not automatically a new-run measurement; use Clear marks followed by Reset run before a fresh comparison and keep earlier notes separately.
Compare a suspected point at the same position on several colours and, if possible, in another app or the display's own menu. The dead pixel vs stuck pixel guide explains how to describe the appearance without assuming an electrical cause.
Measurement limits
The fields support visual inspection but cannot classify panel electronics, measure colour accuracy or establish warranty eligibility. Zoom, scaling, colour management, room light and viewing angle can affect what appears on screen.
Fullscreen may be unavailable in some browsers. Inspect only the area the pattern actually covers, and keep the same brightness and viewing position when comparing colours. A screenshot captures rendered page content and may not show a physical display defect.
Content review and test scope
Content reviewed on 2026-10-10 by ProbeKits Team for correspondence with pattern controls and local-marker readouts; this is not a professional hardware inspection.
Physical-device results: not measured. Automated colour changes and clicks verify software interaction only; a test marker is not a real faulty pixel. Record the display model, browser/version, brightness, room light, zoom, viewing position and repeated visible observation when you make a real-device comparison.
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Screen test for dead and stuck pixels questions
How does a dead pixel test find a fault on my monitor?
The page displays solid colours so you can inspect a location repeatedly. Compare white, black and the primary colours, keeping the same viewing position. A mark that stays in place is useful evidence, but dust, reflections and scaling also need checking. The browser does not inspect panel electronics or automatically classify the cause.
What is the difference between a dead and a stuck pixel test?
A dark point on light fields and a bright point on a dark field describe different observations. Compare the same location across colours before naming it. This stuck pixel test cannot establish whether a subpixel is electrically stuck or whether repair is possible. Use the colour record to explain the symptom to support.
Does this monitor test work on a laptop screen or a phone?
Yes, the page can display fields on a laptop or phone browser, subject to fullscreen and navigation support. Browser chrome, zoom and system scaling affect the visible area. This desktop monitor test does not bypass those layers or certify every physical pixel. Check the exposed area and record the device used.
What does an LCD test pattern show?
An LCD test pattern makes bright, dark or uneven regions easier to compare. Use one colour at a time and keep brightness and room light fixed. The lcd test does not measure luminance, colour accuracy or the panel's electrical state. It supports a visual record rather than an automatic defect certificate.
How do I check a new monitor before the return window ends?
Record repeatable marks on several fields, note the model and check the seller's current return terms. Warranty pixel policies can differ by model and defect type. A clean screen test does not guarantee future behaviour, and a marked point does not by itself establish an entitlement to replacement.
How should I repeat the screen test fairly?
Use the same screen, zoom, system brightness, lighting and viewing position. Compare the same marked location on each colour, then reset before a different device. A screenshot captures page content but may not show a physical panel fault, so keep your visual notes beside any photograph used for support.
What can the screen test not prove?
It cannot prove the electrical cause of a point, repair a failed pixel or establish warranty coverage. It also cannot calibrate luminance or colour accuracy. The screen test shows controlled fields and local marks; follow the monitor check guide for a wider visual comparison.