How to use the dead pixel and screen test
- Clean the screen with a soft dry cloth first, because dust and smudges look like dead pixels. Set the brightness to a level you normally use.
- Press Start full screen test, or choose a color to start on. The page fills the screen with one solid color.
- Move through the colors with a click, a tap, the Space key or the right arrow key. The left arrow goes back. Look at each color for a few seconds and scan the whole screen, including the corners.
- Press Escape or the Exit button when you finish. Note the color and the place of any dot that does not match its surroundings.
What the colors show
Every pixel on a screen is made of three small parts that show red, green and blue. On a black screen, a pixel that stays bright is stuck on. On white, a pixel that stays dark has stopped lighting up and is usually called dead. Red, green and blue each light only one part of every pixel, so a dot that is missing in one of them points to a single failed part. Cyan, magenta and yellow light two parts at once and help confirm what you saw.
A stuck pixel is always lit in one color. A dead pixel is always dark. A cluster of odd pixels in one area, or a line that never changes, points to a different panel fault. Uneven brightness near the edges is a separate matter called backlight bleed and is easiest to see on black in a dim room.
What to do if you find something
Check the screen on a second device or with a second test to rule out dust, a screen protector or a problem with the connection. Do not press on the panel or try repair tricks you cannot undo, because that can damage it. A stuck pixel sometimes fades by itself over time, but a dead pixel usually stays dead.
How many faulty pixels count as a defect depends on the maker and on the store policy, so read the warranty terms before you decide. Take a clear photo of the screen showing the dot. This page only displays colors. It does not record anything and it does not connect to your screen in any way beyond drawing on it. If full screen is not available in your browser, the page covers the browser window instead. Related tools include the screen resolution checker and the click speed test.
Assumptions and limits
- The test shows eight pure colors: black, white, red, green, blue, cyan, magenta and yellow.
- Your browser may scale the page, so a dot on screen can be larger than one hardware pixel on high density displays.
- The test cannot measure brightness uniformity, color accuracy or response time.
- Full screen mode depends on the browser. Without it, a window-covering view is used.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel is dark and never lights up. A stuck pixel is lit in one color all the time. Both are tiny, but a stuck pixel is often easier to see against a dark background.
How can I tell a dead pixel from dust?
Dust sits on the surface and often shows a fuzzy edge or moves when you wipe the glass. A dead pixel stays in the same spot after cleaning and is sharp even when you tilt the screen.
Can a dead pixel be repaired?
Usually not. A stuck pixel sometimes recovers, but a dead one generally stays dark. If the screen is under warranty, check the maker policy on how many faulty pixels qualify for service.
Does this test work on phones and tablets?
Yes. Tap to move to the next color. If the browser blocks full screen, the page fills the window instead, which still lets you inspect most of the screen.