Dead pixel test: full-screen colors, gradients and grid

Fill your screen with 12 test patterns (black, white, red, green, blue, gradients, grid) to spot dead, stuck and hot pixels, backlight bleed and banding.

How to spot a dead, stuck or hot pixel on a screen

A dead pixel stays black on a white background, a stuck pixel keeps one fixed color (red, green or blue) and a hot pixel stays lit on a black background. Step through the full-screen patterns and inspect the whole surface up close, on a clean screen.

Method

  1. Clean the screen: a speck of dust looks like a dead pixel but moves when you wipe it.
  2. Start the test: the page goes full screen (Fullscreen API) and shows the first pattern.
  3. Step through the 12 patterns with the arrow keys, Space, a click or a swipe. Black reveals hot pixels and backlight bleed, white reveals dead pixels, red, green and blue a sub-pixel that is off or stuck, the gradients reveal banding and the grid geometry defects.
  4. Leave with Esc or the ✕ button.

Order of magnitude

A 1920 × 1080 screen has 1920 × 1080 = 2,073,600 pixels, or 6,220,800 red, green and blue sub-pixels. At 24 inches, its diagonal of √(1920² + 1080²) ≈ 2,203 pixels gives 2,203 ÷ 24 ≈ 91.8 pixels per inch, so one pixel measures 25.4 ÷ 91.8 ≈ 0.277 mm. A single defect is 1 pixel in more than two million, so look closely, area by area.

Limits

  • The solid patterns cover every physical pixel, even on a high-density screen; the grid lines are 1 CSS pixel wide, which is 2 physical pixels at a scale factor of 2.
  • The tool changes pattern at most 3 times per second, even with a key held down, and has no flashing mode.
  • If the browser refuses full screen, the pattern covers the window: maximize it.

Sources and dates: WHATWG, Fullscreen API; W3C, WCAG 2.2, criterion 2.3.1 (three flashes) (checked on 29/10/2026)

Frequently Asked Questions

What is the difference between a dead, stuck and hot pixel?

A dead pixel no longer lights up, so it shows as black on the white pattern. A stuck pixel stays on one color (often red, green or blue) and shows on the patterns of the other colors. A hot pixel stays lit and shows as a bright dot on the black pattern.

How do I exit the test's full screen?

Press Esc, or tap the screen and then the ✕ button at the top right. The button reappears for 2.5 seconds at every pattern change and every mouse movement.

Full screen does not work on my phone, what can I do?

Some mobile browsers do not let a page go full screen. The pattern then covers the whole window: rotate the phone, run the test and also scroll to check the area under the address bar.

Why is a faulty pixel so hard to see?

A 1920 × 1080 screen has 2,073,600 pixels. On a 24-inch screen each one measures about 0.277 mm, so look closely, area by area, on a clean screen.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.