Dead Pixel Test – Screen Check
Full-screen colours to find dead and stuck pixels
Tap or press → / Space for the next colour, ← for the previous one, Esc to exit.
Online Dead Pixel & Screen Test
Check a new phone, laptop or monitor in a minute
Start the full-screen test and look closely at the display while it cycles through solid colours. On black, a pixel that stays lit (white or coloured) is a stuck or hot pixel; on white, red, green and blue, a black dot is a dead pixel or a dead sub-pixel. Gray reveals uneven backlight, clouding and dirty-screen effect, the gradient shows colour banding and the checkerboard helps judge sharpness and scaling. Tap the screen or press → and Space to go to the next colour, ← to go back and Esc to exit, or let it change automatically every three seconds. Below, the tool lists your screen’s physical resolution, pixel ratio, colour depth and the measured refresh rate (60, 90, 120, 144 Hz…). Clean the screen first – dust can look like a dead pixel.
Features
8 test screens
Solid colours, gradient, checker
True full screen
Phones, laptops and monitors
Refresh rate
Measured in Hz
Auto cycle
Hands-free every 3 s
Pixel Defects Explained
What you may see
- Dead pixel: always black, visible on white
- Stuck pixel: always one colour (red, green or blue)
- Hot pixel: always white, visible on black
- Backlight bleed: bright edges on a black screen
- Banding: visible steps in the gradient
Before returning a device
- Clean the screen and retest
- Note the position of each defect
- Check the manufacturer’s dead pixel policy (ISO 9241-307 classes)
- Stuck pixels sometimes recover after hours of use
- Test in a dark room for backlight bleed
Frequently Asked Questions
How do I check for dead pixels?
Start the full-screen test, clean the screen and look at each colour from a normal distance. Black dots on bright colours are dead pixels; coloured or white dots on black are stuck or hot pixels.
What is the difference between a dead and a stuck pixel?
A dead pixel never lights up and stays black. A stuck pixel is lit permanently in one colour because a sub-pixel stays on. Stuck pixels can sometimes be revived; dead pixels usually cannot.
How many dead pixels are acceptable?
It depends on the manufacturer’s policy, which often follows ISO 9241-307 pixel classes. Many brands replace panels with even one bright pixel; others allow a few dead pixels.
Is the refresh rate accurate?
It is measured from the browser’s frame timing and rounded to the nearest common value. Browsers may cap it in power-saving mode or on battery.
Does it work on phones?
Yes. On iPhone the test covers the whole visible screen; tap to change colours. Turn brightness up for best results.