Fill your screen with solid colours, gradients and fine patterns to find dead, stuck and bright pixels, spot backlight bleed and measure your refresh rate, all in your browser with nothing uploaded.
Dead Pixel Test – Monitor Test Online
Fill your screen with solid colours, gradients and fine patterns to find dead, stuck and bright pixels, spot backlight bleed and measure your refresh rate, all in your browser with nothing uploaded.
The patterns are drawn in your browser and nothing about your screen is uploaded. Only your option choices are saved, and only in this browser; the flashing warning is never saved, so you confirm it every time.
The Dead Pixel Test fills your whole screen with one colour or pattern at a time, so a faulty pixel has nowhere to hide. It has 23 full-screen views: eleven solid colours and grays, five gradients, and seven fine-detail patterns including a one-pixel checkerboard, colour bars and tiny sharpness text. The single-pixel patterns are sized from your display's real pixel ratio, so a one-pixel line is one physical pixel even at 125% or 200% scaling. Step through with the arrow keys, a click or a tap, let it advance by itself every 2 to 5 seconds, and leave with Esc. A Your screen panel shows your resolution in CSS and physical pixels, colour depth and aspect ratio, and times your refresh rate. Everything is drawn on your device.
Features
23 full-screen views: 11 solid colours and grays, 5 gradients and 7 detail patterns
Black, white, red, green, blue, cyan, magenta and yellow for dead, stuck and bright pixels, plus a black screen for backlight bleed in a dark room
Gray, red, green and blue ramps and a 16-step gray bar that expose banding and lost shadow detail
One-pixel checkerboard and line patterns sized to your real pixel ratio, and a framed crosshatch grid for geometry and cropped edges
Tiny sharpness text on black and on white that reveals blur and colour fringes from a non-native resolution
Arrow keys, click, tap or swipe to move, optional auto-advance every 2, 3 or 5 seconds, and Esc, a lost window or a hidden tab to leave
A Your screen panel with CSS and physical resolution, scaling, aspect ratio, colour depth and a measured refresh rate you can copy
A stuck-pixel exerciser behind a photosensitivity warning, with a draggable 200 px square and a timer
How to use the Dead Pixel Test
Wipe the screen with a soft dry cloth, set the browser zoom to 100% and dim the room
Press Start full-screen test, or open a single pattern from the tiles
Move through the patterns with the arrow keys, a click or a tap, and look closely at every colour, especially the corners and edges
Press Esc to leave, then note which pattern showed each dot and where on the screen
Press Measure refresh rate if you also want to know what your display delivers
Example
Input
Start full-screen test · 24-inch monitor at 1920 × 1080 · room lights dimmed
Output
White: 1 black dot, 40% from the left and 62% from the top → dead pixel
Black: no bright dots; faint glow in the bottom-left corner → light backlight bleed
Red, green, blue: no stray dots
Gray ramp: smooth · 16-step gray: all 16 bars distinct
Refresh rate: 60 Hz (measured 59.9 Hz, jitter ±0.12 ms)
A note like this, with the pattern and the position of each dot, is what a seller or the maker's support will ask for.
Common errors & troubleshooting
A dot disappears when I wipe the screen. — That was dust or a smudge, not a pixel fault. A real dead or stuck pixel stays exactly where it is, wipe after wipe and pattern after pattern. Clean the screen with a soft, dry microfibre cloth and look again.
The test does not cover the whole screen. — Browsers that cannot switch to true full screen, such as Safari on iPhone, fill the page instead. Hide the browser toolbar or add the page to your home screen. On a computer, allow full screen if the browser asks, or press F11 first.
The single-pixel patterns look blurry or shimmer. — Set the browser zoom to 100% and the display to its native resolution. At any other zoom or resolution the picture is scaled and neighbouring pixels blend together, however carefully the pattern is sized.
The refresh rate reads 60 Hz on my 144 Hz monitor. — Many monitors stay at 60 Hz until you raise the rate in your system's display settings. A browser in battery-saver mode can also cap animation at 60 Hz. Change the setting, keep the tab in front and measure again.
Frequently asked questions
How many dead pixels are acceptable after running the Dead Pixel Test?
There is no single number. The ISO 9241-307 standard sorts panels into pixel-fault classes, from one that allows no faulty pixels to ones that allow a few per million, counted by type: always dark, always lit and single sub-pixels. What you can claim is set by the maker's own warranty, though. Some replace a panel for one bright pixel, others want several faults or a cluster. Look up the policy for your model and keep a note of which pattern showed each dot.
What is the difference between a dead, stuck and hot pixel in the Dead Pixel Test?
A dead pixel is permanently dark, so it is a black dot on every colour. A stuck pixel has one or two sub-pixels stuck on, so it shows as a red, green, blue, cyan, magenta or yellow dot, easiest to see on black. A hot pixel, also called a bright pixel, is stuck fully on: a white dot on a black screen. Dust and smudges are none of these. They sit on the surface and wipe off, while a real fault stays where it is.
Which colours should I check first in the Dead Pixel Test?
Start with white and black, which together catch most faults: dead pixels show as black dots on white, and stuck or bright pixels show as coloured or white dots on black. Then run red, green and blue, where one faulty sub-pixel stands out against its own colour. Finish with the grays and gradients to check even brightness and smooth shading. Dim the room for the dark patterns and look at the corners and edges as well as the centre.
Why do the gradients in the Dead Pixel Test show stripes or bands?
A ramp is drawn from a limited set of brightness steps, 256 per colour on a typical 8-bit screen, so faint steps can show on the gray ramp even on a good panel. Clear bands point to less colour depth: budget panels often use fewer bits and dither the rest, and a reduced colour mode or the monitor's own picture processing can make it worse. Use the 16-step gray bar as a check: you should be able to tell every neighbouring bar apart.
Does the stuck-pixel exerciser in the Dead Pixel Test really fix pixels?
Rarely, and never for a dead pixel. A dead pixel has sub-pixels that are permanently off, which software cannot repair. A stuck pixel is sometimes a sub-pixel held in one state, and rapid colour changes can jolt it loose, but the effect is unreliable: it may take minutes, may wear off later, and often does nothing at all. Treat the exerciser as a last try, stop after a few minutes, and do not press on the screen. Never use it if flashing lights affect you.
What does the refresh rate measurement in the Dead Pixel Test mean?
It times about two seconds of animation frames, takes the typical gap between frames and snaps the result to the nearest standard rate such as 60, 120 or 144 Hz when it is within 3 percent. The figure is the rate this tab actually receives, so a browser cap, battery saver or a monitor set below its maximum will lower it. The jitter value shows how evenly the frames arrive. If your monitor is rated higher, raise the rate in your system's display settings and measure again.
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