QuickDeviceTest

Device test / Dead pixel test

Dead pixel test

Fill your screen with solid colours, one at a time, and look for dots that don't match. Takes a minute and is worth doing on day one with any new monitor, laptop or phone.

Clean the screen first, then start. Tap or press → to change colour; Esc to exit.

How to scan properly

  1. Wipe the screen with a dry microfibre cloth; dust looks a lot like a dead pixel.
  2. Dim the room and sit at your normal distance, then lean in section by section.
  3. On each colour, sweep left to right, top to bottom. Note any dot's position.
  4. If you find one, check it's not on the glass by viewing from a slight angle: dust moves relative to the grid, a pixel doesn't.

Stuck or dead? What's inside one pixel

Each LCD pixel is three sub-pixels, red, green and blue, each with its own tiny transistor. A stuck sub-pixel is always on; a dead pixel stays dark. Pick a fault and a test colour to see how it shows up.

Fault:
Test colour:

Choose a fault above. Dead pixels stand out on white; stuck ones stand out on black.

Questions

How do I check for dead pixels?

Clean the screen, open the full-screen test and step through the colours. On black, look for bright dots (stuck pixels); on white, look for dark dots (dead pixels); on red, green and blue, look for dots of the wrong colour.

What is the difference between a dead and a stuck pixel?

A dead pixel stays dark because it gets no power. A stuck pixel has one or more sub-pixels permanently on, so it shows red, green, blue or a mix on screens where it should be dark.

Can a stuck pixel be fixed?

Sometimes. Stuck pixels occasionally recover with time, or with gentle pressure through a soft cloth while the screen is on. Dead pixels usually can't be revived. Rapidly flashing "fixer" videos are unproven and can trigger photosensitive seizures, so we don't offer one.

Is one dead pixel covered by warranty?

It depends on the manufacturer's pixel policy (many follow the ISO 9241-307 classes). Some replace a panel for a single bright pixel, others require several. Check before the return window closes: test new screens on day one.

Does it work for phone and OLED screens?

Yes. On OLED, also look for faint image retention (burn-in) on the grey screen.