How to test for dead pixels
- Clean the screen, then press Start full-screen test, or click one of the colours to start from it.
- Look slowly across the whole screen, edge to edge, for any dot that doesn’t match the colour around it.
- Click, or press Space or →, for the next colour and ← to go back. Press Esc when you’re done.
Dead, stuck and hot pixels
Every pixel on your screen is made of three tiny parts, called subpixels: one red, one green and one blue. They mix to make every colour you see. A faulty pixel is one where those parts don’t do what they’re told.
| Fault | What you see | Best colour to spot it |
|---|---|---|
| Dead pixel | A black dot that never lights up | White |
| Stuck pixel | A dot stuck on one colour, often red, green or blue | Black, or a colour that contrasts with it |
| Hot pixel | A white dot that is always lit | Black |
Not every dot is a pixel fault. Dust and smudges sit on top of the screen and wipe away. If a dot moves when you look from a different angle, it’s on the surface, not in the panel.
Testing a new monitor
Test a new screen on the first day, while returning it is still simple. Dim the room, start the test and look at each colour for a few seconds. Work across the screen in sections rather than staring at the middle, since faults near the edges are easy to miss. A phone camera zoomed in on a suspicious spot helps confirm what you see.
The black screen also shows backlight bleed: light leaking in at the edges or corners. A faint glow is common on LCD screens, especially at an angle. Bright patches that are clearly visible from straight in front are worth raising with the seller. If you find a faulty pixel, note where it is and which colours it shows on, as support teams usually ask.