How to inspect a pixel defect before selling a monitor

You spot a tiny dot on your monitor and want to know what you are selling before you list it. It could be dust on the screen, a pixel that is stuck on a color, or a pixel that no longer lights up. Those look similar at a glance, but they are not the same fault.

Use the Display Test to check the screen against solid colors. If a pixel appears stuck rather than dark, the Stuck Pixel Fixer can try a brief flashing pattern. Neither test can guarantee a repair, so first document what you see.

Inspect the pixel defect

1. Open the Display Test on the monitor you plan to sell. If you use more than one screen, make sure you are looking at the intended display.
2. Check the screen against solid colors, including white, black, red, green, and blue. Look at the same spot on each color and note whether the dot stays in exactly the same place.
3. Clean the glass gently with a clean, soft microfiber cloth, then check the spot again. Do not press hard on the panel or try to rub the dot away.
4. If the spot stays bright or colored, open the Stuck Pixel Fixer and try its flashing pattern briefly. Stop if the rapid flashing is uncomfortable. Then return to the color checks and see whether anything changed.
5. Photograph the screen with the defect visible, and take a second photo from farther away to show where it is on the monitor. Include the color that makes it easiest to see.

Keep the photos unedited if you are using them to show a buyer the condition. A close-up can help, but a wider image gives useful context and helps show that the spot is on the screen rather than a mark on the camera lens.

What the result means

The dot disappears when the surface is cleaned

It was likely dust or residue on the glass, not a pixel defect. Check the screen again under a different color and angle before deciding it is clear. Avoid scraping the panel, which can damage its coating.

The dot stays dark on every color

A pixel that remains black may be a dead pixel, or a small group of dead subpixels. A pixel is made from red, green, and blue subpixels, so a fault in one subpixel can also look like a colored dot rather than a completely black one. Record the color and position instead of guessing at the exact panel fault.

The dot stays bright or shows one color

This may be a stuck pixel or a stuck subpixel. The flashing pattern from the Stuck Pixel Fixer may help a stuck pixel change state, but it may not. A result that stays the same after a short attempt should be documented as an ongoing defect, not described as fixed.

The mark moves, changes shape, or appears only in an image

It may be part of the picture, a browser overlay, or another display issue rather than a single faulty pixel. Check the same location on multiple solid colors and, if possible, with another computer or video source connected to the monitor.

You cannot see the spot in person, but it appears in a photo

Camera sensors can create their own colored dots, and reflections or sharpening can make a tiny mark look different. Use your eyes to confirm the defect. Try another photo with the camera straight in front of the screen and avoid zooming in digitally.

Rule out setup problems

1. Check the monitor's resolution. Use the display's recommended or native resolution so the image is not being scaled unexpectedly. In Windows 11, open Settings › System › Display and check Display resolution. On macOS, open System Settings › Displays and check the selected resolution.
2. Check another source. Connect the monitor to a different computer or device, if available. If the dot remains fixed in the same physical spot on the panel, that points more strongly to a screen defect than to the original computer's image.
3. Reconnect the video cable. Turn off the monitor and source device, then firmly reconnect both ends of the cable. If you have another compatible cable or port, test it too. A signal problem more often causes lines, flicker, or larger areas of image corruption than one tiny fixed dot.
4. Check the monitor's on-screen menu. Open the monitor's own settings menu. If the dot is visible over that menu as well as over the computer image, the panel is likely involved. Menu names vary by model, so use the monitor's own controls and manual rather than changing an unrelated picture setting.
5. Keep the test brief. If the pixel remains stuck, do not press on the screen or run flashing patterns for a long time. Repeated pressure can damage the panel, and a software pattern cannot replace a failed pixel.

When it is a panel defect

A spot that remains in the same physical location across solid colors, a different cable, and another source is strong evidence of a monitor defect. A browser test can help you see and describe it, but it cannot inspect the panel electronics or prove the exact cause.

Before listing the monitor, note the defect's approximate position, color, and whether it appears on every background. Include clear, honest photos and mention whether the flashing test changed anything. Do not promise that a stuck pixel will recover. If the monitor is still covered by a warranty, check the manufacturer's pixel policy before selling it, since acceptable pixel counts vary by model and policy.

Why a pixel looks different on different colors

Each pixel contains red, green, and blue subpixels that combine to make the colors on screen. A subpixel that stays on can stand out on a dark background, while one that stays off may be more visible on a bright background. That is why a single white screen is not enough to inspect a suspected defect.

For a photo record, include at least one image with the spot easy to see and one image showing its location on the full screen. You can also compare your findings with how to check a monitor for dead pixels.