Dead Pixel or Stuck Pixel?
One is a dot that never lights. The other is a dot that never goes out. They look for different backgrounds, they mean different things, and one of them is often not a pixel at all.
A dark pixel is one whose subpixels are all permanently off: a black dot you can only see on a light background. A bright or colored dot is a subpixel that is permanently on, and it stands out on black. Find them with a white field, then a black one, then red, green and blue. If the mark is irregular in shape and shows mainly on white, check for dust before you assume it is a fault at all.
Nearly every argument about a new screen starts the same way: someone sees a dot, calls it a dead pixel, and is told it is a stuck one. The words matter, because the two faults hide on different backgrounds.
What the words mean
A screen’s picture is made of pixels, and each pixel is made of three subpixels. Dell puts it plainly: each pixel contains one red, one green and one blue subpixel, and the three “work together like a team.” What you see as a single colored dot is those three mixing.
Apple describes what goes wrong underneath: “Occasionally, a transistor may not work perfectly, which results in the affected subpixel remaining off (dark) or on (bright).” That single sentence is the whole distinction.
Stuck off — the dark kind
Dell calls this a dark pixel defect: all three subpixels permanently turned off, appearing as "a black dot that you can see on white or colored backgrounds." Against black it is invisible, because black is what it already shows.
Stuck on — the bright kind
Dell calls this a bright pixel defect: all three subpixels permanently turned on, giving "a bright white dot that's always visible, especially on dark backgrounds." If only one subpixel is stuck on, the dot is red, green or blue instead of white.
In everyday use people call the dark kind a dead pixel and the bright kind a stuck pixel. Manufacturers write “dark” and “bright” instead, and those are the words their policies use, so they are the ones to use with support.
Telling them apart in two minutes
- 1
Open a white field full screen and look for a dark or colored dot. The Dead Pixel Test does this, and changes color only when you ask it to.
- 2
Switch to black. A dot that was invisible on white and is bright here is a subpixel stuck on. A dot that vanished is a dark one.
- 3
Step through red, green and blue. A dot that shows on one primary only is a single faulty subpixel. A dot in the same place on all three is the whole pixel.
- 4
Note the position, not the count. One pixel appears on several fields, so counting fields inflates the total.
A dark pixel and a bright one are each other's blind spot: neither field can show you both.
Before you call it a fault: is it dust?
This is the check people skip, and it is the one that saves the most time.
Apple notes that “in some cases a small piece of dust or other foreign material may appear to be a pixel anomaly,” that foreign material is typically irregular in shape and most visible against white backgrounds, and that surface dust can be removed with a lint-free cloth, while trapped material needs professional service.
A pixel fault is a precise square in the same place whatever is on screen, and cleaning does not change it. Dust is a ragged shape that often moves or disappears when you wipe. Clean the screen first.
| What you see | Shows up on | Most likely |
|---|---|---|
| A precise black square | White and colored fields | A dark pixel |
| A precise white dot | Black, especially | A bright pixel |
| A precise red, green or blue dot | Black, and the matching primary | One subpixel stuck on |
| An irregular mark | White, mainly | Dust or foreign material |
What can be done about each
The honest answer is short. A dark pixel is a transistor that is not switching, and no picture on the screen changes that. A bright subpixel is the same fault in the other direction.
ScreenTail does not offer a stuck-pixel fixer and does not describe how to build one. The usual method flashes colors rapidly, and rapid flashing can trigger seizures in people with photosensitive epilepsy. No result from such a tool is worth that risk.
What is left is the maker. Apple’s advice, for a pixel anomaly that concerns you, is to take the product in for closer examination at an Apple Store, an Apple Authorized Service Provider or an Independent Repair Provider. Other makers publish their own routes and their own limits.
Two things are worth knowing before that conversation:
- The distance matters. Dell assesses pixel faults at normal viewing distance, which it puts at about 35 to 50 cm for a standard monitor. A fault you can only find by leaning in is judged at the distance you would actually sit.
- The policy is theirs, not general. Allowances differ by maker, by product line and by region. The only number that counts is the one in your own maker’s published policy, with the date you read it.
What this cannot settle
This page tells you which kind of fault you are looking at. It cannot tell you whether your display qualifies for a replacement: that is a policy question, and the policies differ. It measures nothing either — a browser paints a color, and you do the judging.
If you have not run the full check, the Monitor Test shows the fields in the order that makes each fault visible, and the Backlight Bleed Test covers the other thing people find on black, which is not a pixel fault at all.
Questions
Is a colored dot a dead pixel?
It is a pixel with something wrong, but not a dark one. A pixel has a red, a green and a blue subpixel. If one of them is stuck on while the others behave, the pixel shows as a colored dot rather than a black one.
Can I fix a stuck pixel myself?
ScreenTail does not offer a fixer, and does not describe one: those tools flash colors rapidly, which can trigger seizures in people with photosensitive epilepsy. Apple's advice for a pixel anomaly you are concerned about is to have the display examined at an Apple Store, an Apple Authorized Service Provider or an Independent Repair Provider. Other makers publish their own procedures.
How do I know it is not dust?
Apple notes that foreign material is typically irregular in shape and most visible against white backgrounds, and that surface dust can be removed with a lint-free cloth. A pixel fault is a precise square, always in the same place, and does not move when you wipe.
How many are allowed before I can return the display?
That is set by the maker and the product line, not by a general rule, and the policies differ. Check your own maker's published pixel policy, and note that Dell, for example, assesses pixel faults at normal viewing distance rather than with your nose against the glass.
How this guide was made
The definitions here are quoted from the manufacturer pages listed below, with the date each was retrieved. The test procedure is the one ScreenTail's own Dead Pixel Test performs, described from the tool as it is built.
No repair method is described. Every widely circulated remedy for a bright subpixel involves flashing colors rapidly, which this site does not build or explain. No acceptable-defect counts are given either: those are per maker and per product line, and belong in a warranty guide that quotes each policy with its date.
- 01Definitions of a bright pixel defect, a dark pixel defect and a subpixel, and the viewing distance at which faults are assessed: Dell, Display Pixel Guidelines — retrieved Sep 23, 2026.
- 02A transistor that does not work leaving a subpixel off or on, dust and foreign material being mistaken for a pixel anomaly, and what to do about it: Apple, About LCD display pixel anomalies — retrieved Sep 23, 2026.