A new monitor, laptop or phone has millions of pixels, and a small number of them failing is still common enough that manufacturers write policies about it. The best time to look is the first day, while the shop's return window is open: a return is usually far easier than a warranty claim. This guide walks through a careful check with our screen test, explains the difference between dead pixels, stuck pixels and the faults that look like them, and covers what pixel-fault policies typically say. Policies and consumer law differ by maker and country, so treat the numbers here as background and read your own warranty terms.
Prepare the screen and the room
- Clean the screen with a dry microfibre cloth. Dust on a white screen looks exactly like a dead pixel; a speck that moves when you wipe was never a pixel.
- Set the screen to its native resolution and 100% browser zoom, so one pattern pixel is one screen pixel.
- Dim the room for the black and bleed checks, then use normal light for the rest.
- Use your normal brightness, not maximum. Backlight bleed always looks worse at full brightness.
The check, pattern by pattern
Start the screen test and step through the patterns with the arrow keys, looking at the whole surface for 10 to 20 seconds each, then up close at anything odd.
- White: dark dots are dead pixels or dust. A phone camera zoomed in on the spot shows whether it is a whole pixel or one subpixel.
- Black: bright dots are stuck pixels or "hot" pixels. In a dark room, also look at the edges and corners: brighter patches there are backlight bleed on LCD panels; uneven cloudy patches in the middle are clouding.
- Red, green, blue: a dot that stays dark on all three is a dead pixel. A dot that is bright on black, invisible on red and visible on green and blue is a stuck red subpixel. Cycling through primaries is what tells these apart.
- Yellow, cyan, magenta: each lights two subpixels at once and catches subpixel faults the primaries make hard to spot.
- Grey 50%: tint, uneven brightness and, on OLED, image retention, faint outlines of a taskbar or keyboard shortcuts bar.
- Gradients: on a 1920-pixel-wide screen each of 256 grey levels is about 7.5 pixels wide. Visible steps that are much wider suggest 6-bit output, a colour profile, a night-light mode or the panel's own processing; switch those off before you conclude anything.
- Checkerboard and lines: at native resolution they look like an even grey. Moiré or blur means scaling.
Write down each fault: what it looks like, on which colours, and its position (for example "bright green dot, 3 cm from the left edge, 8 cm from the top"). Take a photo with the pattern showing; it is the evidence for a return.
Dead, stuck, or something else?
| What you see | Likely cause | Will it change? |
|---|---|---|
| Dark on every colour | Dead pixel (transistor fault) | Rarely recovers |
| Lit in one colour on black | Stuck subpixel | Sometimes recovers |
| White on black | Hot pixel (all subpixels on) | Rarely recovers |
| Dot that moves when wiped | Dust on the surface | Gone |
| Dot that looks blurred, larger than a pixel | Dust or debris inside the panel layers | Permanent, usually covered like a pixel fault |
| Bright edges on black | Backlight bleed (LCD) | Permanent; sometimes eases slightly |
| Ghost image on grey | Image retention (OLED) or burn-in | Retention fades; burn-in does not |
Stuck subpixels sometimes respond to rapidly flashing colours shown on the spot for a while, or to very gentle pressure through a soft cloth with the screen off. Neither is guaranteed, pressure can create new damage, and some warranties exclude physical damage. If the screen is still returnable, return it rather than experimenting.
What pixel-fault policies usually allow
Many manufacturers base their policies on pixel fault classes that came from the old ISO 13406-2 standard, withdrawn and replaced by the ISO 9241-300 series (ISO 9241-307) in 2008. Its widely quoted Class II, which most monitors used to be sold under, allowed per million pixels up to 2 always-on pixels, 2 always-off pixels and 5 faulty subpixels. Scaled to common screens:
| Screen | Pixels | Class II allowance (rounded) |
|---|---|---|
| 1920 × 1080 | 2.07 million | about 4 bright, 4 dark, 10 subpixel faults |
| 2560 × 1440 | 3.69 million | about 7 bright, 7 dark, 18 subpixel faults |
| 3840 × 2160 | 8.29 million | about 17 bright, 17 dark, 41 subpixel faults |
That is the scale of the old benchmark, not a promise: today each maker sets its own policy. Some offer a "zero bright pixel" guarantee for a period; others count only faults in the central area, or require a minimum number before replacing a panel; phones and laptops are often treated differently from monitors. Look for "pixel policy" or "pixel defect" in the warranty terms for your exact model.
Making a claim stick
- Check on day one. A shop's return window, where one applies, is usually the easiest route because no pixel count is needed.
- Document it: photos with the test pattern visible, the position of each fault, and the date.
- Describe it in the policy's terms: bright, dark or subpixel, how many, and where.
- Keep the box and accessories until you are sure.
- Know your local rules. Consumer protection for faulty goods varies by country and can go beyond the manufacturer's warranty; a consumer association or the seller can tell you what applies.
Common mistakes
- Testing at maximum brightness in a dark room and calling normal bleed a defect.
- Mistaking dust for a dead pixel, or a scaled image for a blurry panel.
- Testing only black and white, which misses most stuck subpixels.
- Pressing hard on a stuck pixel before deciding whether to return the screen.
- Waiting weeks, until the return window has closed.
A fifteen-minute check on the day a screen arrives is the cheapest insurance there is. While you are checking a new laptop, the keyboard tester covers the other part that is hard to return later.