A dead pixel check takes two minutes and needs nothing but this page. Go fullscreen and click (or press the arrow keys) to cycle the display through the five diagnostic colors — white, black, red, green, blue. Scan the panel slowly on each color: any dot that stays black, stays lit, or shows the wrong color is a faulty pixel.
Do this test in the return window of every new monitor, laptop, phone or TV you buy. A single bright dead pixel found on day two is a warranty replacement; found on day thirty, it is a life sentence.
What people use it for
New device check
Run the full five-color cycle on any freshly bought display before the return period expires. Clean the screen first — dust impersonates dead pixels convincingly.
Stuck pixel diagnosis
A pixel stuck on red, green or blue shows on the opposite color fields. Identifying which sub-pixel is stuck is the first step to attempting a revival.
Used-device inspection
Buying a second-hand phone or monitor? This test runs from the seller's own browser in under a minute, right in front of them.
Frequently asked questions
What is the difference between dead and stuck pixels?
A dead pixel is permanently black (no power reaches it). A stuck pixel is frozen on one color — red, green or blue — and unlike a dead one, can sometimes be revived by rapid color cycling.
Can dead pixels be fixed?
Truly dead ones, no — that is physical damage. Stuck pixels sometimes recover after minutes of rapid color changes; our red, green and blue screens can be used for that exercise.
How many dead pixels justify a warranty return?
Policies vary by manufacturer and pixel class — many replace a panel for a single bright pixel in the central zone, but several dark pixels near the edge may be within tolerance. Check the vendor's pixel policy and test within the return window.