Dead Pixel Test & Monitor Test: Full-Screen Color, Gradient & Grid

Inspect solid colors, grayscale, gradients, and geometry grids in a distraction-free full-screen display test.

Monitor & Dead Pixel Tester fills your entire screen with eight solid reference colors, a black-to-white gradient, and a scaling grid, plus an auto-cycling mode that steps through every color automatically for a hands-off pixel sweep. It is a set of controlled full-screen visual references for your own eyes to inspect, not a colorimeter, and not a substitute for measuring instruments if you need calibrated numbers.

How to run a dead pixel test

  1. Wipe the screen with a dry microfiber cloth so a speck of dust is not mistaken for a dead pixel, and set the brightness you normally use.
  2. Click Auto-cycle dead-pixel test, then choose Enter fullscreen on the control panel so browser toolbars stop covering the edges of the panel.
  3. Let the eight colors advance every 1.8 seconds, or click Pause cycle and step with the left and right arrow keys or the Previous color and Next color buttons.
  4. Sweep every corner and edge: on white and the light grays look for dark dots (dead pixels), on black look for lit dots (stuck pixels), and use red, green and blue to see which subpixel is at fault.
  5. The control panel sits near the bottom center and hides that strip while it is shown, so press Esc or Exit test when you are done and recheck anything you are unsure about.

Eight colors chosen to expose different failure modes

The color set is black, white, pure red, pure green, pure blue, and three flat grays at twenty-five, fifty, and seventy-five percent brightness. A pixel stuck permanently on one color shows up clearly against black, where it should be dark, or against the two colors it is not showing; a pixel that is dead, stuck off entirely, shows up as a dark spot against every bright swatch, especially white. The pure red, green, and blue screens isolate whichever single subpixel channel might be misbehaving, since a busy full-color image can hide one bad subpixel inside itself.

Each swatch opens in a dialog covering the entire browser viewport; clicking anywhere on a solid-color screen, or pressing the arrow keys, advances to the next or previous color without needing to back out to the selection screen each time.

Gradient and grid mode test something the flat colors cannot

The gradient mode renders a continuous black-to-white sweep left to right, which is where visible banding, hard steps between shades instead of a smooth transition, becomes obvious, a symptom of limited color depth or poor dithering rather than anything a solid color would reveal.

The grid mode draws one-pixel black lines every sixteen pixels over a mid-gray field, useful for spotting scaling artifacts, geometry distortion, or overscan and underscan issues where the displayed image does not line up cleanly with the panel's actual pixel grid, problems a flat color or a gradient would not show at all.

Running the auto-cycle sweep properly

The auto-cycle option steps through all eight solid colors automatically, holding each one for just under two seconds before advancing, so you can watch the whole panel without clicking through colors manually while scanning for a stuck or dead pixel. It can be paused at any point if something catches your eye and needs a longer look before moving on to the next swatch.

True fullscreen mode is available as a separate option and improves accuracy by removing browser chrome and any surrounding desktop color from view, though the test still fills the entire browser viewport reasonably well even if the fullscreen request is denied or unsupported on your setup.

Stuck pixel or dead pixel found: what to try next

Checking a monitor for backlight bleed

Open the Black swatch, enter fullscreen, and dim the room. Keep the monitor at the brightness you really use, since cranking it to maximum exaggerates any glow. Look for lighter patches or clouds along the edges and in the corners, and view the screen straight on, because IPS glow shifts with viewing angle while true bleed stays put. A camera often overstates bleed, so judge it by eye.

Dead pixel testing on phones, tablets and TVs

On any device the test opens as an overlay that fills the browser's visible area. The Enter fullscreen button asks the browser's Fullscreen API to hide its toolbars; some mobile browsers do not grant that to web pages, and the test then shows a notice that fullscreen is unavailable. When that happens, the strips under the address bar and system bars cannot be checked from this page, so scroll or rotate the device to see as much of the panel as possible.

For a TV, the simplest route is to connect a computer over HDMI, drag the browser window onto the TV and use fullscreen there; a TV's built-in browser may also work, but whether it allows fullscreen depends on that browser. This combination of devices has not been specifically tested.

What a screen full of color cannot measure

Questions people ask about Monitor & Dead Pixel Tester

What is the actual difference between a stuck pixel and a dead pixel?
A stuck pixel is lit but showing one fixed, wrong color no matter what is supposed to be displayed there, so it stands out clearly against black or against colors it is not showing. A dead pixel is unresponsive and stays dark, showing up as a small dark spot against any bright background such as white or a light gray swatch.
Why does the test cycle through colors automatically instead of me picking each one?
The auto-cycle mode holds each of the eight reference colors on screen for just under two seconds and steps through them on its own, letting you scan the whole panel methodically for a stuck or dead pixel without breaking your visual focus to click a button between every color.
Can this test tell me if my monitor's colors are accurate?
No — it shows fixed reference colors for a visual inspection, but it has no way to measure actual color output, gamma, or calibration the way a hardware colorimeter would. Treat what you see as a rough visual check, not a calibrated color-accuracy report you can rely on.
What does the grid mode actually check for?
It is meant for spotting geometry, scaling, and overscan or underscan problems, cases where the displayed image does not line up cleanly with the monitor's own pixel grid, which a solid color or a gradient would not reveal on their own.
Can a stuck pixel be fixed?
Sometimes. A pixel stuck on one color may come back after rapid color flashing or light pressure, though results vary and pressure carries risk. A pixel that stays black on every swatch is usually dead for good. Check your return and warranty terms before attempting either approach.
How many dead pixels are acceptable under warranty?
There is no universal number. Each manufacturer publishes its own pixel policy, often counting bright and dark defects separately and sometimes caring where they sit on the screen, and some models promise zero bright pixels. Look up the policy for your exact model and record what this test shows.
How do I test my monitor for backlight bleed?
Show the black swatch full screen in a darkened room at your everyday brightness setting, then look for glowing edges or corners. Move your head: glow that shifts with angle is typical IPS glow, while light leaking from the same spot from every angle points to backlight bleed.
Does this dead pixel test work on a phone or TV?
The colors fill whatever the browser shows, so it runs on phones, tablets and TV browsers. Hiding the toolbars depends on the browser allowing fullscreen for web pages, which some mobile browsers do not, and those covered strips cannot be checked. For a TV, connecting a computer by HDMI is the most dependable option.

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Content reviewed 2026-09-27.