Clean your screen first. Enter full-screen, then tap or use the arrow keys to change colour and inspect every corner. Press F to toggle the stuck-pixel fixer, Esc to exit.
Hardware TesterFree browser tests for your webcam, mic, keyboard, mouse, controller and display.
Dead pixel test: check your screen for dead and stuck pixels
This dead pixel test fills your whole screen with solid colours so faulty pixels stand out. Cycle through red, green, blue, white, black and more, and look closely for any dot that's the wrong colour or doesn't change. It works on any monitor, laptop, phone or tablet screen, runs full-screen in the browser, and needs nothing installed. The ideal quick check when buying a new display or inspecting a used one.
Dead pixels vs stuck pixels
A dead pixel stays black on every colour because it receives no power, it's easiest to spot on a white field. A stuck pixel is frozen on one colour, usually red, green or blue, and shows up as a bright dot against the opposite colours. The difference matters: stuck pixels can often be revived, while a truly dead pixel usually can't.
How to run the test
Clean your screen first so dust isn't mistaken for a fault. Enter full-screen, then step through each colour with a tap or the arrow keys and examine the whole surface, including the corners. Note the position of anything that looks wrong on each colour. Press Escape or tap the exit control to leave full-screen at any time.
Trying to fix a stuck pixel
Stuck pixels sometimes recover if their sub-pixels are rapidly cycled, which is what the built-in fixer does. It flashes fast colour noise over the screen. Run it over the stuck area for a few minutes; gentle pressure with a soft cloth while it runs can help. It doesn't always work, and it can't fix a dead (unpowered) pixel, but it's harmless to try.
Dead pixel policies
Manufacturers allow a small number of pixel defects before a panel qualifies for warranty replacement, and the threshold varies by brand and screen class. Documenting exactly which colours reveal the fault, and where, gives you the evidence you need when making a claim. Everything here runs locally in your browser. Nothing about your screen is uploaded.
Frequently asked questions
A dead pixel gets no power and stays black on every colour, so it's clearest on a white screen. A stuck pixel is frozen showing one colour (often red, green or blue) and stands out against the opposite colours. Stuck pixels can sometimes be revived; dead pixels usually can't.
Clean the screen, enter full-screen, and cycle through each solid colour with a tap or the arrow keys. Examine the whole surface (including the corners) on every colour and note any dot that stays black or shows the wrong colour. Black reveals stuck (always-on) pixels; white reveals dead (always-off) ones.
Sometimes. Rapidly cycling the sub-pixels can unstick them, which is what the built-in fixer does by flashing fast colour noise. Run it over the affected area for a few minutes, optionally with gentle pressure from a soft cloth. It won't fix a truly dead pixel, but it's safe to try.
It depends on the manufacturer. Most allow a certain number of defective pixels before a panel qualifies for replacement, and the limit varies by brand and screen grade. Recording which colour shows the fault and where it is on the screen gives you evidence for a warranty claim.
Yes. Any screen with a browser works: monitors, laptops, phones, tablets and most smart TVs. The test simply fills the display with solid colours, so it's equally valid for LCD, IPS, VA and OLED panels. Nothing is installed or uploaded.