Screen test
Cycle full-screen colours to find dead pixels, stuck pixels and backlight problems on your monitor or phone.
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What this screen test checks
Filling the whole display with one solid colour at a time makes flaws that hide behind normal content stand out: dead pixels, stuck pixels, backlight bleed and uneven brightness. Cycling through white, black and the primary colours is the same method repair shops use.
Reading the results
Look for any dot that stays the wrong colour on every screen — a spot that is always black is a dead pixel, while one stuck on red, green or blue is a stuck pixel. Patchy brightness or glowing edges on a black screen indicate backlight problems. Clean the screen first so a speck of dust isn't mistaken for a pixel fault.
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.
- How do I exit the test?
- Press Esc at any time to leave full-screen and return to the page.
- Can this fix a stuck pixel?
- This test only helps you find faults; use the fixer mode in our dead pixel test to attempt a repair.
- Should I run it in a dark room?
- Yes — dimming the lights makes faint backlight bleed and stuck pixels far easier to see.