Dead Pixel Test
Cycle full-screen colours to spot dead or stuck pixels.
Running the test
Start the full-screen test and click through solid white, black, red, green, blue and grey, examining the screen closely on each. Clean the screen first โ a speck of dust does a very convincing dead-pixel impression. Arrow keys move between colours; Esc exits.
A pixel that stays black on every colour is dead. One showing a constant wrong colour โ a red dot on a blue screen โ is stuck: it is powered but frozen on one subpixel, which is why each primary colour gets its own test screen.
What can be done about them
Stuck pixels sometimes recover โ on their own, or with software that flashes rapid colour changes over the spot. Dead pixels are permanent: no power reaches the pixel, and no software can restore it.
The practical advice is about timing: run this test the day a new screen arrives. Every manufacturer has a dead-pixel policy โ many require a minimum number of defects before replacing a panel, some premium brands replace for a single one โ and the strongest position you will ever have is inside the retailer's return window, where the panel's policy does not matter. Laptops and phones are covered by the same logic. While auditing a new screen, the refresh rate test confirms the panel runs at its advertised speed, and the resolution checker confirms scaling is set sensibly.
Frequently asked questions
What is the difference between a dead and a stuck pixel?
Dead pixels get no power and stay black on every colour. Stuck pixels are frozen showing one colour and are visible on the screens that should mask them. Stuck ones sometimes recover; dead ones do not.
Can a dead pixel be fixed?
No โ dead means unpowered, and software cannot repair it. Stuck pixels occasionally respond to rapid colour cycling or simply recover with time.
How many dead pixels justify a replacement?
Policies vary from any-single-pixel (premium brands) to five or more depending on position. Check your manufacturer's policy, and test within the retailer's return window when the bar is much lower.
Why test with different colours?
Each pixel is red, green and blue subpixels. A stuck subpixel only shows against the right background, so a full check needs each primary plus black and white.