display
Dead Pixels vs. Stuck Pixels: How to Tell, and What Your Warranty Actually Covers
A dead pixel and a stuck pixel look similar and are completely different failures. How to distinguish them in 30 seconds, what the ISO pixel-fault classes allow, and whether "pixel fixer" videos do anything.
You found a tiny dot on your new monitor. Before you start a warranty claim, it’s worth knowing that the two defects people both call “dead pixels” have opposite causes, opposite appearances, and opposite odds of fixing themselves — and that most manufacturers will not replace a panel over one of them.
What a pixel actually is
An LCD pixel isn’t one thing. It’s three subpixels — red, green, blue — each a liquid-crystal shutter in front of a shared white backlight. The shutter twists to let more or less light through, and the color you see is the mix of the three.
That structure is the whole explanation for both failure modes:
- Dead pixel (dark dot). The subpixel’s transistor has failed and the shutter is stuck closed. No light gets through. On a white background it’s a black dot. On a black background it’s invisible, because it’s already doing what the rest of the screen is doing.
- Stuck pixel (bright dot). The shutter is stuck open — permanently passing its color. On a black background it’s a bright red, green, blue, cyan, magenta, yellow, or white dot. On a white background it can vanish entirely.
That inversion is the diagnostic. A dead pixel hides on black; a stuck pixel hides on white. Which is why testing on one background color is useless, and why any real screen test cycles through solid white, black, red, green, and blue at minimum.
| Dead pixel | Stuck pixel | |
|---|---|---|
| Cause | Transistor failure — subpixel receives no drive | Subpixel stuck at full drive |
| Appears on white | Black dot | Usually invisible |
| Appears on black | Usually invisible | Bright colored dot |
| Color | Always black | Red, green, blue, or a mix |
| Can it self-heal? | Essentially never | Sometimes |
| Common cause | Manufacturing defect | Defect, or a static image left on screen |
There’s a third case worth naming: a partially stuck subpixel, where one of the three is stuck but the other two work. That shows up as a dot that’s the wrong color rather than plain black or plain bright — a pixel that renders magenta on a white field, say. It’s a stuck-pixel variant, and it’s the easiest to miss because it only appears on some colors.
Finding them: what to actually look at
Run through full-screen solid colors, one at a time, and look at the whole panel — not just the center. Order matters less than coverage, but a sensible sweep is:
- Black — finds stuck and bright subpixels. Do this in a dark room; ambient light washes out faint ones.
- White — finds dead pixels and dark dots.
- Red, then green, then blue — finds partially stuck subpixels, which hide on both black and white. A subpixel stuck-off shows as a dark dot only on its own color.
Two things people forget:
- Clean the screen first. Dust and dried spray produce dots that are indistinguishable from defects until you wipe them. Genuinely, most “dead pixels” are debris.
- Look from straight on. Off-axis viewing on VA and TN panels creates color shifts that read as defects.
Our screen test runs the whole sequence full-screen with keyboard navigation so you’re not moving a mouse cursor across the area you’re inspecting.
While you’re there: the defects that aren’t pixels
Solid colors also surface panel problems that are not individual pixel failures, and are much more likely to be what’s actually bothering you:
- Backlight bleed and IPS glow. On a black screen in a dark room, light leaking in from the edges or corners. Bleed is uneven and localized; IPS glow is a broad, viewing-angle-dependent silvery haze that shifts as you move your head. Glow is inherent to IPS and not a defect. Bleed is a matter of degree.
- Clouding / mura. Uneven brightness patches, best seen on a mid-gray field rather than black or white. Gray is the honest test for uniformity — extremes hide it.
- Banding. Visible steps instead of a smooth ramp on a gradient. Often a signal-chain problem (color depth, cable, or GPU output settings) rather than the panel.
- Sharpness and scaling. A one-pixel checkerboard or single-pixel line pattern should look like a clean, even texture. If it shimmers, blurs, or produces moiré, you’re likely not running the display at its native resolution, or a TV is applying overscan.
The screen test includes gray fields, gradients, and pixel grids for exactly these, because in practice they account for more “my monitor looks wrong” complaints than dead pixels do.
Do pixel-fixer videos work?
For stuck pixels: occasionally, and the mechanism is real. Rapidly cycling colors under the stuck subpixel exercises the liquid crystal and can sometimes unstick it. Gentle pressure with a soft cloth on the exact spot, while the screen cycles, is the other common technique. Reported success rates are all anecdotal, but stuck pixels genuinely do sometimes resolve — including on their own, with no intervention.
For dead pixels: no. The transistor is dead. Nothing you display on the screen can repair a broken transistor, and no amount of color cycling will change that. Every “fix any dead pixel!” video is either mislabeling stuck pixels as dead, or selling you nothing.
A real caution on the pressure technique: pressing hard on an LCD can create new, permanent defects — you can damage the layer stack or cause pressure mura that doesn’t fade. If you try it, it should be barely more than a touch. Personally I’d rather live with one stuck pixel than gamble a panel on it.
What your warranty actually says
This is where expectations and reality diverge most. Almost nobody replaces a monitor for a single dead pixel.
The industry reference is ISO 13406-2, published in 2001, which defined four pixel-fault classes. It was superseded in 2008 by ISO 9241-307, which carried the same class structure forward. The allowances are expressed per million pixels, across three defect types: type 1 (permanently bright), type 2 (permanently dark), type 3 (a defective subpixel).
| Class | Type 1 (bright) | Type 2 (dark) | Type 3 (subpixel) |
|---|---|---|---|
| I | 0 | 0 | 0 |
| II | 2 | 2 | 5 |
| III | 5 | 15 | 50 |
| IV | 50 | 150 | 500 |
Most consumer monitors are sold as Class II. Note what that means on a 4K panel: roughly 8.3 million pixels, so the per-million allowance scales up — a Class II 4K display can ship with a meaningful number of faults and still be exactly to spec.
Two important caveats before you cite a class number at a support agent:
- Manufacturers set their own policies and interpret the classes loosely. Published thresholds vary by brand, by product line, and by panel size, and some count subpixels where others count whole pixels. The ISO class is a starting point for the conversation, not a contractual guarantee.
- “Zero bright dot” warranties exist and are worth paying for if this matters to you. Several premium lines (professional and high-end gaming monitors especially) explicitly guarantee zero bright pixels, above the ISO Class I baseline. That promise is a purchasing decision, not something you can negotiate after the fact.
Practical advice: test the panel the day it arrives. Return windows are unconditional and short; warranty pixel policies are conditional and stingy. A 60-second check on day one is worth far more than a warranty claim on day 40.
Test your display
- Screen Test — full-screen solid colors for dead and stuck pixels, gray fields and gradients for uniformity and banding, and pixel grids for sharpness. Works on monitors, laptops, phones, and TVs.
- Webcam Test and Mic Test — the same idea for your other hardware.
- Keyboard Test — for when the problem is input rather than output.
Nothing is uploaded; the tests run entirely in your browser.