How to Test for Dead and Stuck Pixels

A few pixels that look wrong are common on new screens, and easy to miss until you stare at a plain color. A quick test with solid colors will find them.

Dead, stuck and hot pixels

A dead pixel stays black on every color because it receives no light. A stuck pixel stays on one color, for example always red or green, while its neighbors change. A hot pixel stays white. Usually they are single tiny dots.

On OLED screens each pixel makes its own light, so a dead pixel shows as a tiny black dot on any bright color. On LCD screens a stuck pixel is the common fault.

How to run the test

• Clean the screen first, so dust or a fingerprint is not mistaken for a pixel.
• Go to a dim room and set the screen to its normal brightness.
• Open the Dead Pixel Test and press F for fullscreen.
• Step through black, white, red, green and blue. Look at the whole screen at each step, then move closer and scan again.
• Also try the cyan, magenta and yellow screens, which mix two subpixels and show partial faults.

What the colors show

A black dot on white or any bright color is a dead pixel. A bright dot on black is a stuck or hot pixel. A dot that appears only on one color points to one faulty subpixel (the red, green or blue part of a pixel).

What to do if you find one

Check how many there are and where. Most makers set a limit before they will replace a screen, and the rules differ by brand and by product, so read your warranty or return policy.

Stuck pixels sometimes recover on their own or after the screen has been on for a while. Dead pixels usually do not. Do not press hard on the glass, because that can damage the display.

When to test

Test as soon as you unbox a monitor, phone or laptop, while returns are still easy. Test a used screen before you pay for it, and again after any repair.