Dead pixel test
Bought a new phone, laptop, monitor or TV — or a second-hand one? Before the return window closes, check the screen for dead pixels (always black) and stuck pixels (always red, green or blue). Thisdead pixel test fills your whole screen with solid colours one after another, so a faulty pixel stands out against the background. It takes about a minute and works on any device with a browser.
How to use it
- Clean your screen and turn the brightness up.
- Tap Start full-screen test.
- On each colour, scan the screen slowly from corner to corner. Tap or press → for the next colour.
- Press Esc (or tap the last colour) to exit.
What to look for on each colour
| Screen colour | Reveals |
|---|---|
| Black | Stuck or “hot” pixels that stay lit |
| White | Dead (black) pixels and dust under the glass |
| Red, green, blue | Sub-pixels that are dead or stuck on another colour |
| Grey | Uneven backlight, clouding and banding |
Example
On a new laptop you spot a tiny dot that is green on the black screen and invisible on the green screen: that's a stuck green sub-pixel. A dot that's black on white, red, green and blue is a dead pixel. Note its position and report it to the seller or brand with a photo.
More device checks
- Test your microphone and camera with the mic & webcam test.
- Sending a photo of the faulty spot to the seller? Shrink it first with the image compressor.