[Clacky](https://clacky.app/) / [Free tools](https://clacky.app/tools/)

# Dead pixel test

Fill your whole screen with one colour at a time to find dead pixels (always black), stuck pixels (always one colour) and backlight bleed. Handy for a new Mac or a second-hand display.

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**Clacky**FileEditViewWindowHelp

**Hi! It’s all free 👋**Click an app to open it. Drag a window by its top bar.

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-   [Clacky Island](#live)

It runs right here, on the little Mac. Drag the window, open other apps from the Dock.

## How to check for dead pixels

1.  Clean the screen first: dust looks a lot like a dead pixel.
2.  Press **Start full-screen test**. Click, or press → or space, for the next colour; ← goes back; Esc ends.
3.  Look slowly across the screen on each colour.

## What you might see

-   **Dead pixel:** a dot that stays black on every colour, easiest to see on white.
-   **Stuck pixel:** a dot that stays red, green or blue, easiest to see on black.
-   **Backlight bleed:** brighter patches near the edges on black, best seen in a dark room.

Apple and most makers have a policy on pixel faults; check your warranty if you find one on a new display.

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## Questions

### How do I test my MacBook for dead pixels?

Open this test, go full screen and look at each colour, especially white (for dead pixels) and black (for stuck pixels).

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

A dead pixel doesn’t light up at all, so it’s black everywhere. A stuck pixel is lit in one colour all the time. Stuck pixels can sometimes recover; dead ones rarely do.

### Can a website fix a stuck pixel?

Pixel “fixers” flash colours fast. It sometimes helps a stuck pixel, but fast flashing can be harmful for people sensitive to it, so this test doesn’t flash.

## More free tools

-   [Keyboard testerPress every key, see which ones work.](https://clacky.app/tools/keyboard-tester/)
-   [Mouse testEvery button, the wheel and double-clicks.](https://clacky.app/tools/mouse-test/)
-   [CPS testClicks per second, 1 to 60 s.](https://clacky.app/tools/cps-test/)
-   [Webcam testYour camera, its resolution and fps.](https://clacky.app/tools/webcam-test/)
-   [Microphone testLive level, waveform, 5-second playback.](https://clacky.app/tools/mic-test/)
-   [What is my screen resolution?Resolution, Retina scale, viewport, Hz.](https://clacky.app/tools/screen-resolution/)
-   [Mac keyboard symbols⌘ ⌥ ⇧ ⌃: names, click to copy.](https://clacky.app/tools/mac-keyboard-symbols/)
-   [Typing Test](https://clacky.app/typing-test/)