Dead Pixel Test
Pick a color to begin, or start with black. Look for any dot that differs from its surroundings.
Click, Space or the right arrow for the next color. Left arrow for the previous one. Esc to exit.
How to use
- Clean the screen first, since dust and fingerprints look like dots. Turn the brightness up.
- Press Start full screen, then click or press the right arrow key to move through black, white, red, green, blue and gray. Press the left arrow to go back and Esc to exit.
- Look closely at each color from about 30 cm away. A pixel that stays a different color on every screen is stuck; one that stays black on a white screen is dead.
How it works
Every pixel is made of red, green and blue sub-pixels. A solid color makes all of them show the same thing, so a faulty one stands out against a perfectly even background.
A dead pixel stays black on every color, because its sub-pixels get no light. It is easiest to see on white. A stuck pixel is frozen on one color, such as bright red, green or blue, and shows best on black. A hot pixel stays white on every screen.
Black checks for stuck and hot pixels, white for dead pixels, and red, green and blue check each sub-pixel on its own. Gray makes uneven brightness and banding easier to see.
FAQ
How do I fix a stuck pixel?
A stuck pixel can sometimes be freed. Switch off the screen, press gently on the spot with a soft, damp cloth over your finger, then turn it on while still pressing. Flashing-color videos help some people, but there is no guarantee. A truly dead pixel cannot be repaired.
Is one dead pixel covered by warranty?
It depends on the maker. Many follow the ISO 9241-307 classification and only replace a screen above a certain number of bad pixels. Check the warranty terms and any return window before you decide.
Why does the page not go full screen on my phone?
Some mobile browsers, notably Safari on iPhone, do not allow the full screen function for web pages. The test still covers the whole viewport; hide the browser bars by scrolling or adding the page to your home screen.
Will this test damage my screen?
No. It only shows normal solid colors. Avoid leaving a bright static color on OLED screens for a long time, as a precaution against burn-in.