Dead pixel test
A dead pixel hides against ordinary content and only shows up against a flat colour. This test fills the screen with eight of them, one after another, so a bad pixel has nowhere left to hide.
The test opens full screen. Space — next · Arrow keys — back and forward · Esc — exit
Your browser blocked full screen. The test still works in this window, but a full-screen view is more reliable — try pressing F11.
Did you find a dot that stayed the wrong colour?
How to run the test properly
The test is only as good as the conditions you run it in, and three things throw it off more than anything else.
Clean the screen first. A speck of dust on a black field is indistinguishable from a stuck white pixel, and you will find far more dust than pixels. Use a dry microfibre cloth, and do not press hard on an LCD — pressure marks look like faults of their own for a few seconds afterwards.
Turn the brightness up. Dark faults on a dim screen are easy to miss entirely.
Get close, then move. Look at the screen from around 30–50 cm and scan in bands rather than trying to take in the whole panel at once. A single pixel is roughly a quarter of a millimetre across on a typical 27-inch 1440p monitor — it is genuinely small.
Press space to move to the next colour, arrow keys to go back and forward, A to cycle automatically every three seconds, and Esc to leave. Each colour catches a different fault: a pixel stuck on red is invisible on the red screen and obvious on the green one, which is why the test runs through all eight rather than just black and white.
Reading what you find
| What you see | On which background | What it is |
|---|---|---|
| Black dot | White and every colour | Dead pixel — no power reaching it |
| Coloured dot | The complementary colours | Stuck pixel — frozen in one state |
| Bright white dot | Black | Hot pixel — sub-pixels stuck fully on |
| Dot only on one colour | One background only | Single stuck sub-pixel |
| Soft glow near an edge | Black only | Backlight bleed, not a pixel fault |
| Smudge that moves as you tilt your head | Any | Dirt on the screen or your glasses |
A stuck sub-pixel is the most common finding of all and the easiest to overlook. Each pixel is made of a red, a green and a blue element, and one of the three can fail on its own. The result is a dot that only appears on some backgrounds, and it is usually only visible from very close up.
Windows 11
Run the test in full screen and turn off anything that alters what reaches the panel:
- Night light (Settings → System → Display) warms the whole image and will tint every field you look at.
- HDR (Settings → System → Display → Use HDR) changes how white and black are mapped. Turn it off for pixel testing and back on afterwards.
- Auto brightness / content adaptive brightness on laptops dims the screen as the picture darkens, which makes the black field look uneven. It is under Settings → System → Display → Brightness.
If pressing F11 does not give you a fully clean screen, check that the taskbar is set to auto-hide.
macOS
- True Tone and Night Shift (System Settings → Displays) both shift colour temperature. Switch both off first.
- On a MacBook, disable automatically adjust brightness in the same panel, otherwise the black field will visibly fade in and out.
- ProMotion displays change refresh rate on the fly. That does not affect this test, but it does affect the refresh rate test later in the sequence.
If the screen is new
Test it the day it arrives, not a month later. Return windows are short, and pixel faults present from new are far easier to argue than ones that appear later. Photograph anything you find with the camera close to the panel and the surrounding area in frame, so the dot is clearly on the screen rather than on the lens.
Common questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel receives no power at all and stays black on every background — the transistor driving it has failed and there is no way to bring it back. A stuck pixel still has power but is frozen in one state, so it shows as a bright red, green, blue or white dot. Stuck pixels sometimes unstick after being cycled rapidly through colours.
How many dead pixels are normal?
More than zero, on most screens. Manufacturers work to pixel fault classes defined in ISO 9241-307; the vast majority of consumer displays ship as Class II, which permits a small number of faulty pixels and sub-pixels per million. That is why a single dead pixel is very often refused as a warranty claim. Check the specific policy for your model before you start a return — some premium monitor lines carry a zero-bright-pixel guarantee that ordinary models do not.
Can this test damage my screen?
No. It displays static colours, which is exactly what your screen does all day. The one thing worth knowing is that OLED panels dislike a static image held for a long time, so do not leave a single colour on screen for tens of minutes — press space and keep moving.
Does the test work on a phone or a TV?
Yes. On a phone, hold it in landscape and turn the brightness up. On a TV, open this page in the TV browser, or cast the tab — the fill covers whatever screen renders it. Dust and smears look a lot like dead pixels at TV viewing distance, so clean the panel first.
Why does my screen show faint dots on the black screen only?
That is usually not a pixel fault. Faint bright patches on black are backlight bleed or IPS glow, which come from the lighting behind the panel rather than the pixels themselves. The backlight bleed test separates the two.