How to check a used monitor for dead pixels
How to test for dead and stuck pixels, and what counts as a fault.
Dead vs stuck pixels
A dead pixel stays black on every colour. A stuck pixel stays lit in one colour, usually red, green or blue. Stuck pixels can sometimes be revived with a pixel-flashing tool; dead pixels cannot.
The test
Show full-screen solid colours (white, black, red, green, blue) and look closely at the panel from about 30cm. A browser-based dead-pixel test is enough.
- Clean the screen first so dust doesn't fool you
- Check the corners and edges
- Photograph anything suspicious for a return claim
What's acceptable
Manufacturers' pixel policies vary. Many allow a few defects on new panels. For a used monitor, ask the seller to state the pixel condition in writing, and use eBay's returns if the item isn't as described.