Phone Dead Pixel Test

A single dead pixel is invisible on normal content. Put a clean red field across your whole screen and a black dot appears out of nowhere. Here’s how to check your phone display thoroughly and know what you’re actually looking at.

Run the test on your phone

Tap Full screen on the test above so a solid color fills the display edge to edge, including the notch area. It works in Safari, Chrome, and Firefox on both iOS and Android, no download needed.

Tap through each color in sequence or turn on Auto-cycle and let it rotate. Don’t rush. Each color exposes a different failure mode, and a partial fault only shows on one or two of them.

What each color reveals

Black is the most important field to check first. A stuck pixel glows red, green, or blue against a dark background, so it stands out immediately. White, red, green, and blue catch dead pixels: dots that stay stubbornly dark while everything around them matches the fill color. Cyan, magenta, and yellow each test two subpixels together, catching partial faults the primaries miss.

A camera or magnifier helps. At 400 ppi, that dot is about 0.1 mm wide. Hard to spot without help.

Dead, stuck, or hot pixel

A dead pixel gets no power. It stays black on every color. A stuck pixel is locked at full brightness on one channel, so it glows red, green, or blue against whatever background the screen shows. A hot pixel has all three subpixels firing at once, which makes it appear bright white on any fill, including dark ones.

Dead pixels are permanent. The transistor is gone. No software fixes that. Stuck pixels sometimes clear with rapid color cycling because the cell isn’t dead, just unresponsive, and voltage changes can kick it loose. Hot pixels sit in the same category as stuck: sometimes fixable, often not.

OLED phones vs LCD phones

The failure modes look the same from the outside but happen differently inside. On an LCD panel the backlight runs behind the liquid crystal layer, so a dead pixel is a spot where the crystal is permanently blocking light. On OLED each pixel emits its own light, so a dead OLED pixel produces nothing at all, not even a faint glow. That makes dead pixels on OLED phones slightly harder to see on dim fills, since there’s no backlight leak around the spot.

OLED phones fail this way more than LCDs because individual emitters can die stuck-on. See a colored dot on an OLED phone? It’s more likely stuck than dead, which means better odds of clearing it.

If you find something

Run the test before the return window closes. Phone warranties handle pixels differently by tier. Samsung’s Galaxy S series and Apple both publish a zero defect policy for bright dots. A sub-$300 Android may allow two or three stuck pixels before the panel qualifies as defective under the ISO 9241-307 class your device was sold under. Pull up the spec sheet before you decide whether to push for a replacement.

For stuck pixels, running Auto-cycle for five to ten minutes subjects the cell to rapid voltage changes. Recovery isn’t guaranteed, but it costs nothing and sometimes works. Physical pressure on the spot isn’t worth trying on a phone: phone panels are thinner than monitor panels and can crack at a fraction of the force. Skip it.

If the pixel is dead and the return window has passed, most users learn to live with it. Dead pixels rarely spread to neighbors. The fault is isolated to one transistor.