What is a pixel fault?
Every pixel on an LCD or OLED screen is built from three smaller parts called subpixels: one red, one green and one blue. The screen mixes them at different brightness levels to make every color you see. With all three fully lit a pixel looks white, and with all three off it looks black.
A pixel fault happens when one or more of those subpixels stops following the picture. Because red, green and blue light add together, the same fault looks different depending on which subpixel failed and on what color the rest of the screen is showing. That is why one spot can be obvious on a white screen and invisible on a black one.
Three things look alike but behave differently. A dead pixel is always dark. A stuck pixel is always lit in a fixed color. Dirt is not part of the screen at all and wipes away.
Dead, stuck or dirt: the quick comparison
Use this table to match what you see to a likely cause. The next section turns it into a step by step check.
| Fault | What fails | What you see | Easiest to spot on |
|---|---|---|---|
| Dead pixel | All three subpixels are off | A black dot | White and colored screens |
| Dead subpixel | One subpixel is off | A cyan, magenta or yellow dot on white | White, or the matching color |
| Stuck pixel | One or two subpixels are always on | A red, green, blue, yellow, cyan or magenta dot | Black |
| Always-on pixel | All three subpixels are on | A white dot | Black |
| Dirt or debris | Nothing in the panel | A fuzzy or uneven spot that can wipe away | Any background |
Makers use different names for these. Dell, for example, defines a bright pixel as one with all three subpixels permanently on and a dark pixel as one with all three permanently off, and it treats a single stuck subpixel as its own case. When a support page uses a different word, match it to the behavior in the table.
Find out which one you have
Answer each question while looking at the spot. You will be asked to open a white screen and a black screen, so keep the tests in a second tab.
First, wipe the screen gently with a dry microfiber cloth. Is the spot still there?
Turn the screen off while you wipe so you can see dust and smudges. Never spray liquid on the screen.
Open the White Screen Test at full brightness. What do you see where the spot is?
Look in a dim room, from a normal distance, then lean in close.
Open the Black Screen Test in a dim room. Is there a lit dot where you first saw the spot?
A lit dot on black is much easier to spot than a dark dot on white.
It was dirt, not a pixel fault
Dust, lint and fingerprints sit on the surface and wipe away. If a spot keeps coming back without you touching the screen, it may be trapped under the glass or inside the panel, so run these questions again with the spot in view.
Dead pixel (all three subpixels off)
A dot that is black on white is a pixel that is not lighting at all. It will also be black on red, green and blue, and it only hides on a black screen. Dead pixels cannot be fixed with software, so check your maker's pixel policy before deciding what to do.
Dead subpixel (one subpixel off)
A cyan dot means the red subpixel is off, magenta means green is off and yellow means blue is off. To confirm, show the matching color: a dead red subpixel turns black on the red screen and disappears on green and blue.
Two subpixels off, one still working
A pure red dot on white means the green and blue subpixels of that pixel are off, and only red still lights. A green dot means red and blue are off, and a blue dot means red and green are off. Note the position and report it as a pixel fault.
Always-on pixel (all three subpixels lit)
A white dot on a black screen is a pixel whose red, green and blue subpixels are all stuck on. It disappears on a white screen, which is why a black screen finds it. Some makers call this a bright pixel.
Stuck subpixel (one subpixel always on)
A red dot on black means the red subpixel is stuck on. It hides when the whole screen is red and shows as yellow on green or magenta on blue. Stuck subpixels sometimes recover without any help, so retest in a few days.
Two subpixels stuck on
A yellow dot on black means red and green are stuck on, cyan means green and blue are stuck on, and magenta means red and blue are stuck on. It looks white on the screen color of the subpixel that is not stuck. For a yellow dot, that is the blue screen.
No pixel fault found
A white screen and a black screen together reveal nearly every single-pixel fault, so this spot is not one. Faint bright patches along the edges are usually backlight bleed, and a soft haze in the corners is usually IPS glow.
What each fault looks like on each color
This chart works out what a single faulty subpixel does on each solid color. It follows from how light adds: red plus green is yellow, green plus blue is cyan and red plus blue is magenta. Find the row that matches your spot, then read across to see where it should show up.
| Fault | White | Black | Red | Green | Blue |
|---|---|---|---|---|---|
| Dead pixel (all off) | Black | Not visible | Black | Black | Black |
| Dead red subpixel | Cyan | Not visible | Black | Not visible | Not visible |
| Dead green subpixel | Magenta | Not visible | Not visible | Black | Not visible |
| Dead blue subpixel | Yellow | Not visible | Not visible | Not visible | Black |
| Stuck red subpixel | Not visible | Red | Not visible | Yellow | Magenta |
| Stuck green subpixel | Not visible | Green | Yellow | Not visible | Cyan |
| Stuck blue subpixel | Not visible | Blue | Magenta | Cyan | Not visible |
| Always-on pixel (all lit) | Not visible | White | White | White | White |
A white screen reveals dark dots and missing colors. A black screen reveals lit dots. If you only have time for two tests, run those two.
Run a five minute check
Use the viewer below to step through the five colors here, or open the full screen tests for a cleaner look. In full screen, tap or click to move to the next color and press Esc to leave.
What to do once you know
- Dirt: wipe it and you are done. Use a dry microfiber cloth, or one barely damp with water, with the screen off.
- Stuck pixel or subpixel: wait a few days and test again, because some recover on their own. Do not press hard on the panel, since that can crack it or create new faults.
- Dead pixel or subpixel: software cannot repair it. The question is whether your maker counts it as a defect.
- Before you buy a used screen: run the white and black screens first. A fault you find before paying is a negotiation, and one you find after is your problem.
Whether a replacement is allowed depends on the maker's pixel policy, the number of faulty pixels and often their position. The ISO 9241-307 display standard includes a pixel fault classification, and many makers publish their own limits instead. Read the policy for your exact model before you contact support, and keep your notes and photo.
- 3subpixels in every pixel: red, green and blue
- 2backgrounds, white and black, reveal nearly every single-pixel fault
- 5 minis enough to check a whole screen
Test yourself
Five quick questions to check you can read the chart.
Frequently asked questions
Is a stuck pixel the same as a hot pixel?
Names vary by maker. Many companies say "bright pixel" or "hot pixel" for a pixel that is always on and looks white, and "stuck pixel" for one locked on a single color. What matters is the behavior: a lit dot that never changes, or a dark dot that never lights.
Can a dead pixel come back to life?
Rarely. A dead pixel is usually a hardware failure, so software tricks do not fix it. Stuck pixels are different, and some recover on their own over days or weeks.
Why does a spot look fine on some colors and wrong on others?
Each pixel is made of red, green and blue subpixels. If only one subpixel is faulty, the dot is only visible when the screen needs that subpixel to be on, or off. The chart in this guide shows what each fault looks like on white, black, red, green and blue.
How many bad pixels are allowed before I can ask for a replacement?
It depends on the maker and the model. Policies usually set a limit per screen and sometimes stricter limits near the center. Read the pixel policy for your exact model before you contact support, and note that some makers offer stronger guarantees on certain ranges.
Do OLED screens get dead and stuck pixels too?
Yes. OLED pixels can fail dark or stay lit. Because an OLED pixel switches fully off, a black screen looks truly black, which makes a lit dot very easy to see.
How do I know the dot is on the screen and not the camera, the glass or the software?
A real panel fault stays in the same spot of the screen on every app and every color. A spot that moves with a window, or is missing from a screenshot, is software. A mark that wipes away or sits on the surface is dirt.