Device tests
Screen test
Cycle full-screen colours to find dead pixels, stuck pixels and backlight problems on your monitor or phone.
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How to use it
- 1Click 'Start screen test' to fill the screen with one colour.
- 2Click to move through white, black, red, green and blue.
- 3Look for spots that stay the wrong colour — those are dead or stuck pixels.
Frequently asked questions
- What is the difference between a dead and a stuck pixel?
- A dead pixel stays black on every colour; a stuck pixel stays one colour. Stuck pixels sometimes recover, dead ones usually do not.
- Why cycle through colours?
- A fault is easiest to see against certain colours — a stuck red pixel hides on a red screen but stands out on black.
- Does this work on phones?
- Yes — it works on any screen with a browser, including phones and tablets.