Dead Pixel Test — Find, Mark and Diagnose Screen Defects

What a dead pixel test actually does

A dead pixel test fills your entire screen with solid colors, one at a time, so that a single misbehaving pixel has nowhere to hide. Against a busy desktop a broken pixel blends in; against a flat field of pure red, green, blue, black or white it stands out immediately. This test cycles through eleven fields — black, white, the three primaries, the three secondaries, and three shades of gray — which together light and un-light every subpixel on the panel.

One thing this test deliberately does not do is claim to detect defects automatically. Your browser only knows what it asked the screen to display; it has no way to know whether a physical pixel actually lit up. Any tool that says it “detected 3 dead pixels” is guessing. That is why this test asks you to mark what you see and then helps you interpret it, rather than pretending to measure the panel.

Dead pixel vs. stuck pixel vs. backlight bleed

These three faults look similar at a glance but are completely different, and only one of them can be fixed in software:

• Dead pixel — receives no power and stays black on every color. On a white field it is a tiny black dot; on black it disappears. Software cannot revive a true dead pixel.
• Stuck pixel — one subpixel is frozen on, so you see a fixed red, green or blue dot, most visible on black. Stuck subpixels can often be recovered by rapidly cycling colors, which is what our Stuck Pixel Fixer does.
• Bright / hot pixel — always fully lit, appearing as a white dot on black. Cycling helps sometimes.
• Backlight bleed — not a pixel fault at all, but light leaking around the edges of an LCD. It shows as a hazy glow on a black screen. Use the Backlight Bleed Test to judge it.

What a dead line of pixels means

Sometimes the defect is not a dot but a full line of pixels — an entire row or column that is dark or stuck. A dead line almost always points to a failed driver or a damaged ribbon cable inside the panel, not to individual pixels. It cannot be fixed in software, and because it is so visible it usually falls well within a manufacturer’s return criteria. Our diagnosis wizard treats a line as its own outcome so you are not sent chasing a fix that can never work.

Getting an accurate result

For the cleanest test, set your display to its native resolution and 100% scaling, turn brightness up, and clean the screen first — most “dead pixels” people report turn out to be dust. Non-integer display scaling and browser zoom can both blur a single-pixel defect, which is why we warn you at the top of the page when your zoom is not 100%. Test in a dark room for the black and backlight fields so your eyes can pick up faint defects.

The five-step loop

This page is built around a simple loop: Test your screen in fullscreen, Mark anything suspicious, Diagnose each mark with a few plain questions, Fix stuck pixels with color cycling if applicable, and Retest to confirm whether the fix worked. Your marks and diagnoses are kept only in this browser tab for the length of your session — they are never sent anywhere.