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How to check a screen for dead or stuck pixels

You have a new monitor, laptop or phone, or bought one second-hand, and want to be sure every pixel works. You will fill the screen with solid colours and look for dots that do not change. Nothing is uploaded.

5-minute read

Today's result Any dead, stuck or hot pixels found, and a clear idea whether a spot is a pixel or dust.

Check within your return window: many shops and makers accept a screen with a set number of bad pixels only in the first days or weeks.

Open Dead pixel test
Contents

  1. Know the three kinds of bad pixel

    A dead pixel stays black (seen best on white), a stuck pixel stays red, green or blue, and a hot pixel stays white (seen best on black).

    Dead = black dot · stuck = coloured dot · hot = white dot.
    Dead = black dot · stuck = coloured dot · hot = white dot.

  2. Clean the screen and dim the room

    Wipe the screen with a dry microfibre cloth, then open Dead pixel test on cv.cm. Dim lights make small dots easier to see.

    Open Dead pixel test

  3. Start the full screen test

    Press Start full screen test. The screen turns black, then white, red, green, blue and gray as you click, press Space or →. ← goes back.

    Black · white · red · green · blue · gray.
    Black · white · red · green · blue · gray.

  4. Scan the screen slowly

    Look at each colour section by section, close up, including corners and edges. Set Next colour to every 5 seconds if you want your hands free.

  5. Rule out dust

    If you see a dot, wipe the spot and look from another angle. Dust moves or blurs; a pixel stays sharp in the same place.

  6. Decide what to do

    Note where each pixel is and on which colours it shows. A stuck pixel may recover after some hours of use; a dead pixel rarely does, so use the return or warranty if it bothers you.

Use with these tools

FAQ

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

A dead pixel gets no power and stays black. A stuck pixel has one or two subpixels always on, so it shows a fixed colour.

Can I fix a stuck pixel?

Sometimes it comes back after hours of normal use. Fast-flashing fixer videos exist, but they can trigger seizures and often do not help, so this test does not flash.

How many dead pixels are acceptable?

It depends on the maker's pixel policy: many allow a few on a new monitor; some promise zero. Check the warranty terms.

Does it work on OLED screens?

Yes. On OLED, also look at gray and white for burn-in: faint shapes left from static images.

Is anything uploaded?

No. The test only draws colours in your browser.