Screen Test Tool
Show full-screen solid colours and a gradient one by one to spot dead pixels, stuck (bright) pixels, burn-in and backlight unevenness with your own eyes. Everything runs in your browser — nothing to install.
Tap the screen or use the arrow keys to change colour; press Esc to exit.
Or jump straight to a specific test screen:
How to read the results
- Dead pixel: a dot that stays black on white or coloured screens.
- Stuck (bright) pixel: a red, green, blue or white dot that stays lit on the black screen.
- Burn-in / retention: a faint ghost of a previous image on a solid colour, common on OLED.
- Uneven backlight: darker corners or light bleed on the white or grey screens.
- Colour banding: visible stripes on the gradient, indicating poor colour depth or calibration.
About the screen test tool
This free online screen test tool displays full-screen black, white, red, green, blue, cyan, magenta, yellow and grey, plus a black-to-white gradient, so you can quickly check for dead pixels, stuck pixels, burn-in, backlight unevenness and colour banding before buying a new phone, tablet, monitor or TV, or when receiving a used device.
Clean the screen first so dust or fingerprints are not mistaken for defects; problems are easiest to see in a dim room at a normal viewing distance. Every test screen is rendered locally in your browser and no data is uploaded.