Dead Pixel Test
One colour at a time, full screen, so a pixel that does not match cannot hide.
Runs entirely in your browser
Loading the tool…
Clean the screen first, so a speck of dust is not mistaken for a pixel. Then press Start: the screen fills with one colour, and a click, a tap or an arrow key moves to the next. Esc leaves. Look for a dot that does not match the rest.
Stuck pixel fixer
A small square that flashes through colours very fast, to be held over a stuck pixel for a few minutes. It sometimes frees a pixel stuck on one colour. It cannot revive a dead one, which is black on every screen.
This flashes rapidly. Do not use it if you have photosensitive epilepsy or are sensitive to flashing light.
A dead pixel is invisible on most of what a screen shows. It takes a flat field of one colour, edge to edge, for a dot that does not match to stand out, and that is all this page is: nine full screen colours, a click apart.
Each one looks for something different. White finds dead pixels, which are black and stay black. Black finds hot and stuck ones, which glow when they should be dark. Red, green and blue find a single failed subpixel, which leaves a dot dark on its own colour and fine on the others. Grey shows uneven backlight and the cloudy patches some panels have in their corners.
Test a new screen while it can still be returned. Most manufacturers publish a pixel policy that allows a few faults before a panel counts as defective, and the returns window is often more generous than the warranty. Look from a normal viewing distance first, then closer, and clean the screen before you start so a speck of dust is not taken for a pixel.
The stuck pixel fixer flashes a small square through colours for as long as you leave it. It is worth ten minutes on a pixel stuck on one colour, and does nothing for a dead one. It flashes fast, so the page asks before starting it.
How to use it
- Clean the screen, then press Start full screen.
- Click, or press an arrow key, to move through the colours.
- Look for any dot that does not match. Esc leaves.
Questions
What is the difference between a dead and a stuck pixel?
A dead pixel gets no power, so it is black on every colour and shows up on the white screen. A stuck pixel has one or more subpixels jammed on, so it shows as a red, green, blue or white dot, clearest on the black screen. A stuck pixel can sometimes be freed; a dead one almost never.
Does the stuck pixel fixer actually work?
Sometimes, for stuck pixels, and it costs nothing to try. Flashing the pixel through its colours can free a subpixel that has jammed. Leave the square over it for ten to twenty minutes. It will not bring back a dead pixel, and nothing in software can, because the transistor that drives it has failed.
How many dead pixels count as a fault?
That depends on the manufacturer, whose pixel policy sets a number before a panel qualifies for replacement. Policies usually allow a few, and are stricter about bright pixels than dark ones and about pixels near the centre. Check the policy for your model, and use the shop's return window if you can: it usually asks fewer questions.
Is it a dead pixel or dust?
Dust sits on the surface, so it moves relative to the image when you move your head, and it wipes away. A pixel is in the panel, so it stays exactly aligned with the grid. Clean the screen with a soft dry cloth first and look again.
Why does the grey screen look patchy?
Uneven backlighting. A little clouding at the edges is normal on many LCD panels, especially on IPS screens viewed in the dark. It is a panel trait rather than a pixel fault, and it is judged by eye: if it bothers you on ordinary dark scenes, that is worth raising with the seller.
Does this work on a phone?
Yes. On Android it goes full screen; an iPhone does not let pages do that, so the colour fills the browser window instead. Turn the phone sideways and scroll the toolbars away for the most screen. The notch and rounded corners are not pixels and cannot be tested.
Is the flashing safe?
Not for everyone, which is why it is behind a tick box. The square is kept small, below the size that guidance on flashing content treats as a seizure risk, but anyone with photosensitive epilepsy or who finds flashing light uncomfortable should not use it.
Your data stays on your device
Everything above runs inside your browser as WebAssembly compiled from Rust. Nothing you type is uploaded, logged or stored on a server. You can load this page once, go offline, and it still works.
This page makes no requests at all, to anywhere. That is not a promise in the copy: it is a Content-Security-Policy header your browser enforces, and connect-src on it is none. Open the network tab and watch nothing happen.