Dead Pixel Test
Run a five-colour sequence across your whole screen and watch closely for any single dot that doesn't change. This works on laptops, external monitors, phones and tablets — no download needed.
How to read the test
Sit close enough to see individual pixels, dim the room if you can, and let each colour fill the screen for a few seconds. A healthy pixel changes colour every time the background changes. Two things to look for:
Dead pixel
Stays black no matter what colour is behind it. It isn't receiving any signal, so it never lights up — most visible against white or bright colours.
Stuck pixel
Stays lit on one colour (often red, green, or blue) no matter what's behind it. Most visible against black. Unlike a dead pixel, a stuck pixel is still receiving power, which is why it's sometimes possible to un-stick it.
Frequently asked
Can a stuck pixel be fixed?
Sometimes. Gentle, brief pressure on the exact spot (screen off) or software that rapidly flashes colours at that pixel can occasionally free it. A true dead pixel, with no power reaching it, generally can't be fixed this way. Try any method at your own risk — check your manufacturer's guidance first.
How many dead pixels is normal?
It depends on the manufacturer and panel size — most use a defect classification standard (such as ISO 9241-307) to decide what qualifies for a warranty replacement, and the acceptable count varies by class. Check your specific manufacturer's warranty policy for the exact threshold on your device.
Should I test a monitor before buying it?
Yes — if you're buying in person, running this page for thirty seconds on the display before you pay is a quick way to catch an obvious defect while you can still ask for a different unit.
Want a plain colour without the auto-cycle, or a custom shade? Use the full colour screen tool.