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Dead Pixel Test

Fill the screen with solid colours to find dead pixels, stuck subpixels, and uneven backlight.

Test field

Black. Finds pixels stuck on.

Colour

Cycling

In fullscreen, tap or click anywhere to move to the next colour. Runs in your browser. Nothing is uploaded.

How to test a screen for dead pixels

  1. Clean the screen first

    Wipe the display with a dry microfibre cloth so dust and smudges are not mistaken for faults.

  2. Start the fullscreen test

    Press Start fullscreen test to fill the entire display with the first solid colour field.

  3. Step through the colours

    Tap or click anywhere to advance, and look closely for any dot that stays black on a bright field or stays lit on the black field.

  4. Note where the faults are

    Press Esc to exit when you have checked every field, including the corners and edges.

Why use this tool

Nine test fields

Black, white, the three primaries, the three secondaries, and a mid grey, covering stuck subpixels and uneven backlight.

Truly fullscreen

The test fills the whole display with a flat colour so nothing borders or distracts from a single faulty dot.

Brighter white field

On a display with a high dynamic range the white field pushes past the usual ceiling, which makes a dim or dead pixel stand out more.

Hands-free cycling

Turn on automatic advance to step through every field on a four second timer while you watch the screen.

Works on any device

Runs on monitors, laptops, tablets, and phones with nothing to install and no extension to grant.

Nothing leaves your browser

There is no upload and no account. The page runs entirely on your device.

About this tool

A dead pixel never lights up, so it shows as a black dot against a bright field. A stuck pixel is the opposite: one subpixel is permanently on, so it shows as a coloured dot against black. Both are easiest to see on a flat, full screen field of a single colour, which is exactly what this test produces.

The order matters. Black comes first because anything permanently lit is obvious against it. White comes second, because anything permanently dark is obvious against that. The red, green, and blue fields then isolate one subpixel at a time, so you can tell which channel is at fault rather than just that something is wrong. Cyan, magenta, and yellow light two channels at once, and a mid grey field exposes backlight bleed and clouding that a pure white field can hide.

On a display that supports a high dynamic range, the white field goes brighter than an ordinary white page, which widens the gap between a working pixel and a failing one. Standard displays show plain white and the test works the same way, just with less headroom.

Clean the screen before you start so dust is not counted as a fault, and check the edges and corners as carefully as the centre. If you want a plain bright panel rather than a colour cycle, the white screen fills the display with adjustable white, and the HDR display test tells you whether this screen can reach past plain white at all.

Frequently asked questions

What is the difference between a dead pixel and a stuck pixel?
A dead pixel receives no power and stays black on every field, including white. A stuck pixel has one or more subpixels permanently on, so it shows as a red, green, blue, or white dot on the black field. Stuck pixels sometimes recover, dead pixels generally do not.
Can this fix a stuck pixel?
No, this is a test rather than a repair. It tells you whether a fault exists and which colour channel it affects, which is what you need before making a warranty claim.
Why does the white field look brighter than a normal page?
Displays with a high dynamic range hold brightness in reserve above ordinary white. The white field asks for that headroom, so a failing pixel stands out more clearly. On a standard display it simply shows plain white.
How do I move between colours?
Tap or click anywhere on the fullscreen field to advance to the next colour. You can also turn on automatic advance before you start, which steps through every field on a four second timer.
How many faulty pixels are normal?
Manufacturers publish their own thresholds, and many treat a small number of faulty subpixels as within specification rather than a defect. Check the warranty terms for your specific model before assuming a replacement is due.
Is anything uploaded?
No. The test draws colours locally in your browser. Nothing about your display is sent anywhere.

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