How this dead pixel test works
Click Start and the page goes full screen with a solid color. Click or press Space to move to the next screen: white, black, red, green, blue, cyan, magenta, yellow and gray, followed by a checkerboard, 1px line patterns, grayscale and color gradients, a uniform gray and a custom color you pick yourself. Press Esc or the × button to leave.
The whole test runs in your browser and nothing is uploaded. Turn the screen brightness up, clean the panel with a dry microfiber cloth, and sit close, because a single pixel is tiny.
What to check
- Dead pixel. A pixel that stays black on every color. It is easiest to see on white, red, green and blue screens.
- Stuck pixel. A pixel locked on one color, usually red, green, blue or white. It stands out on black and on the opposite colors.
- Hot pixel. A pixel that is always fully lit. Check the black screen in a dim room.
- Backlight bleed. Light leaking at the edges or corners of a black screen. It is normal in small amounts. IPS panels also show "IPS glow," a soft haze that shifts as you move your head, which is different from bleed because it does not stay fixed.
- Banding. Visible steps instead of a smooth fade in the gradients. Mild banding is common on 6-bit and 8-bit panels.
- Uniformity. On the gray screen, look for darker patches, tinted corners or vertical stripes.
- Lines and checkerboard. These reveal flicker, shimmering, or pixel inversion artifacts and show whether the panel is running at its native resolution.
Found a bad pixel? Try these fixes
- Rule out dust. Wipe the screen gently. A speck of dust looks like a dead pixel but moves when you wipe it.
- Run the stuck pixel fixer. Choose 5, 10 or 20 minutes. It flashes random colors over the screen, which can free a stuck pixel. Warning: rapidly flashing colors can trigger seizures in people with photosensitive epilepsy, so do not use it if that applies to you or anyone nearby. Place the stuck pixel inside the flashing area.
- Try gentle pressure. With the screen off, press the pixel lightly with a soft cloth wrapped around a pen cap. Use very little force, since you can crack the panel.
- Check the cable and settings. Colored dots or lines across a region can be a loose cable, not a pixel. Reseat the cable and set the native resolution in Settings → System → Display on Windows or System Settings → Displays on macOS.
- Contact the seller. Dead pixels (always black) are permanent hardware damage. Stuck pixels often respond to fixing, but dead ones never do.
Why test your screen
Test a new monitor, laptop or phone on the day you get it. Most manufacturers follow ISO 9241-307 classes, which allow a small number of defective pixels depending on the class and panel size. Many brands accept a return only above a certain count, or only for clusters, so read the warranty before you buy. Photograph the defect and run the test inside the return window. Testing a used display before you buy takes less than two minutes.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel stays black because it gets no power. A stuck pixel is locked on one color such as red, green, blue or white. Stuck pixels can sometimes be fixed, dead pixels usually cannot.
Can a stuck pixel be fixed?
Sometimes. Flashing random colors for 10 to 20 minutes frees many stuck pixels, but there is no guarantee. A pixel that is permanently black is a hardware fault.
Is backlight bleed normal?
A small amount at the edges of a black screen is normal on most LCD monitors. If it is bright enough to bother you in a dark room, check your warranty or return policy.
Is the stuck pixel fixer safe for my screen?
Flashing colors does not damage a healthy panel. It can trigger seizures in people with photosensitive epilepsy, so avoid it in that case.
How many dead pixels are acceptable?
It depends on the manufacturer and the ISO 9241-307 class of the panel. Many brands accept returns only above a set number of defective pixels, so check the warranty.
Does this test work on phones and TVs?
Yes, on any device with a browser. Open the page, go full screen and step through the colors. OLED phones show dead pixels best on a black screen.
What is banding?
Banding is visible stripes in a smooth gradient because the display cannot show enough shades. The gradient screens in this test make it easy to see.
Why does the dead pixel not appear in a screenshot?
A screenshot copies the image data the computer sends, not what the panel actually displays. A faulty pixel is a physical defect in the screen, so it can only be seen on the display itself or in a photo of it.
Is it dust or a dead pixel?
Dust or a speck on the surface can be wiped away with a soft microfiber cloth, while a dead pixel stays in exactly the same spot. Also, dust looks irregular and may show a shadow, but a dead pixel is a sharp square dot.