What is a dead pixel test?

A dead pixel test fills your screen with solid colours one at a time so you can spot pixels that stay black or are stuck on a single colour. Against a flat field, a faulty pixel stands out as a small dot that does not match.

Can a screensaver find dead pixels?

Yes. Cycling through solid full-screen colours is the standard way to find dead and stuck pixels, because each flat colour makes a faulty pixel obvious. This test does exactly that in your browser.

Can a screensaver fix stuck pixels?

Sometimes. A stuck pixel can occasionally be revived by rapidly cycling colours over it, though a truly dead pixel that never lights cannot be repaired in software. This tool helps you find them and may help unstick some.

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

A dead pixel stays black and never lights up, so it is most visible on a white screen. A stuck pixel is frozen on one colour and is easiest to see on a contrasting solid colour.

Is the dead pixel test free, and how do I exit it?

Yes, it is completely free and runs in your browser with no download. Press the ESC key at any time to exit the full-screen test.

Why use pure red, green and blue screens?

A pure red screen drives only the red subpixels, so a stuck subpixel is easiest to spot against its matching field. Cycling through the three shows which colour channel is at fault.

Could a dark spot just be dirt?

Yes, dust and smudges are a common false alarm. Wipe the screen gently with a soft dry cloth and look again; a real pixel defect stays in exactly the same spot.

Dead Pixel Test (Full-Screen Colour Checker)

A dead pixel test fills your whole screen with one solid colour at a time so you can scan for pixels that stay black (dead) or stuck on a single colour. This free tool runs in your browser with nothing to download — pick a colour or auto-cycle through white, black, red, green, blue and more, and press ESC when you are done. Looking at each flat colour full screen makes a faulty pixel easy to spot as a tiny dot that does not match.

How the Dead Pixel Test screensaver works

The test simply paints the entire screen a single, perfectly flat colour with no motion or pattern. Against that even field, a dead pixel shows up as a tiny dot that stays black, and a stuck pixel shows as a dot frozen on red, green or blue, because a healthy pixel should match the colour around it exactly.

Turn the cycle toggle on and the screen steps automatically through a fixed sequence — white, black, red, green, blue, cyan, magenta, yellow and grey — pausing on each so you can inspect the whole display one colour at a time. The interval control sets how many seconds each colour stays up.

With cycling off, the screen holds a single colour of your choice set by the colour picker. A small showInfo readout names the current colour and its hex value, and it uses a difference blend so the label stays readable on any background.

Dead, stuck and hot pixels, and what a flat colour reveals

A flat-panel display is a grid of millions of pixels, each usually built from red, green and blue subpixels. Defects come in a few types. A dead pixel stays dark, because on an LCD its transistor leaves it blocking the backlight. A stuck pixel is always on, frozen on red, green or blue whatever the image. A hot pixel, also called a bright dot defect, stays lit and shows as a bright dot on a dark screen.

Solid colours are the standard way to look for them, because a defect stands out against a uniform field. A black screen exposes bright and stuck pixels, a white screen exposes dark dots, and pure red, green and blue screens help show which subpixel is at fault. Stepping through several colours covers all the cases in a minute or two.

How manufacturers treat these defects varies. Some have a zero-tolerance policy, while others set limits on the total number of defects or on how many may sit in a small area. The ISO 13406-2 standard defined display classes by the number of defects allowed, but manufacturers do not all follow it. Check your product’s policy before assuming a single bad pixel is covered by warranty.

A worked example

With the defaults — colour #ffffff, cycle off, interval 4 and showInfo on — the screen is solid white with the colour name and hex shown faintly at the bottom, good for spotting dark dead pixels. Turn cycle on and it walks through all nine colours, holding each for 4 seconds; lower the interval to 1 to move faster, or raise it toward 10 to study each colour longer.

Settings & tips

Turn on the Cycle toggle to step automatically through white, black, red, green, blue and more without clicking.
Use the Interval slider (1 to 10 seconds) to control how long each colour stays on screen while you inspect it.
With Cycle off, set any single shade in the Colour picker to hold one flat field; black is best for finding bright stuck pixels.

Frequently asked questions

What is a dead pixel test?: A dead pixel test fills your screen with solid colours one at a time so you can spot pixels that stay black or are stuck on a single colour. Against a flat field, a faulty pixel stands out as a small dot that does not match.
Can a screensaver find dead pixels?: Yes. Cycling through solid full-screen colours is the standard way to find dead and stuck pixels, because each flat colour makes a faulty pixel obvious. This test does exactly that in your browser.
Can a screensaver fix stuck pixels?: Sometimes. A stuck pixel can occasionally be revived by rapidly cycling colours over it, though a truly dead pixel that never lights cannot be repaired in software. This tool helps you find them and may help unstick some.
What is the difference between a dead pixel and a stuck pixel?: A dead pixel stays black and never lights up, so it is most visible on a white screen. A stuck pixel is frozen on one colour and is easiest to see on a contrasting solid colour.
Is the dead pixel test free, and how do I exit it?: Yes, it is completely free and runs in your browser with no download. Press the ESC key at any time to exit the full-screen test.
Why use pure red, green and blue screens?: A pure red screen drives only the red subpixels, so a stuck subpixel is easiest to spot against its matching field. Cycling through the three shows which colour channel is at fault.
Could a dark spot just be dirt?: Yes, dust and smudges are a common false alarm. Wipe the screen gently with a soft dry cloth and look again; a real pixel defect stays in exactly the same spot.

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