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Localtools

Dead Pixel Test

Fill your screen with solid colors to spot dead, stuck and hot pixels in seconds.

Colors in the test

  • Black
  • White
  • Red
  • Green
  • Blue
  • Gray

In the test: click, tap, → or Space for the next color, ← for the previous one, Esc to stop.

How to use

  1. Clean the screen with a soft, dry cloth so dust is not mistaken for a faulty pixel.
  2. Press "Start test". The display fills with black, the first test color.
  3. Look over the whole screen slowly, then click, tap or press → to move to white, red, green, blue and gray.
  4. Note the position of any dot that does not match the color around it, then press Esc to finish.

How the test works

Every pixel on an LCD or OLED screen is made of three tiny subpixels: red, green and blue. Mixing them at different strengths creates every color you see. When one of them fails, the pixel can no longer show some colors correctly, but in a normal photo or web page the fault is easily lost among millions of other pixels.

A solid, full-screen color removes that distraction. On pure black, every subpixel should be off, so any light dot is a fault. On pure white, every subpixel should be on, so a dark dot is a fault. The red, green and blue screens each light just one subpixel type, which reveals pixels that are stuck on or off for a single color. The final gray screen helps you spot faint dots and uneven areas that only show up at medium brightness.

Dead, stuck and hot pixels

  • Dead pixel: stays black on every color. The transistor that controls it has failed, so it no longer lets light through (LCD) or emits light (OLED). Most visible on the white screen.
  • Stuck pixel: shows a single color, such as a bright red, green or blue dot, on every background. One or more subpixels are stuck on. Most visible on black and on the colors it does not match.
  • Hot pixel: a stuck pixel that is always fully white. It is easy to see on the black screen. Camera sensors have hot pixels too, but those appear in photos, not on your monitor.

Partial faults also exist: a subpixel that is dimmer than the others, or one that only fails on certain colors. These look like a faint tint and are easiest to judge on the gray screen.

What to do if you find one

First, make sure it is not dust: dust can usually be wiped off and often looks soft or slightly out of focus. Then note where the pixel is and on which colors it is visible. If the screen is new, check the seller’s return policy and the manufacturer’s pixel policy, and contact them while you are still within the return window. A photo of the pixel on the colored test screen helps your claim.

Stuck pixels sometimes recover after a few hours of normal use. Gently massaging the area with a soft cloth while the display is switched off occasionally helps, but pressing too hard can damage the panel. Many “pixel fixer” programs flash rapidly changing colors on the stuck area. Those flashes can trigger seizures in people with photosensitive epilepsy, and the evidence that they work is mixed, so this page does not offer them.

Tips for an accurate check

Turn the brightness up, sit at your normal viewing distance and look at the screen straight on. Scan slowly in rows from one corner to the opposite one, and give each color a few seconds. On a large monitor or TV it helps to check one half of the screen at a time. Automatic color changes are handy when you want both hands free, while clicking through yourself lets you take as long as you need on each color.

Backlight bleed and uneven brightness are separate from pixel faults. To check for them, show a full-screen black or white page with the white screen tool in a dark room.

Frequently asked questions

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

A dead pixel stays black on every color because it no longer receives power. A stuck pixel stays one color, usually red, green, blue or white, because one or more of its subpixels are permanently on.

Which color shows a dead pixel best?

White. A dead pixel appears as a black dot on a white screen. Stuck and hot pixels are easiest to see on black, where a lit pixel stands out clearly.

Can dead or stuck pixels be fixed?

Truly dead pixels usually cannot. Stuck pixels sometimes recover on their own or after gentle pressure with a soft cloth while the screen is off. Some tools flash colors rapidly to unstick them; rapid flashing can trigger seizures in people with photosensitive epilepsy, so this test deliberately does not do it.

How many dead pixels are acceptable?

It depends on the manufacturer. Many follow the ISO 9241-307 pixel fault classes and accept a few faulty pixels on a large screen, while some offer a zero-dead-pixel guarantee. Check the warranty terms and test within the return period.

Does this work on phones and TVs?

Yes. Open the page on a phone or tablet, or in your smart TV's browser, and start the test. On iPhone the colors fill the browser window rather than the whole screen, so rotate to landscape to cover more of it.

Is the automatic color change safe for people sensitive to flashing?

The fastest automatic setting changes color once every two seconds, which is far slower than the flash rates known to trigger photosensitive seizures. You can also leave it off and change colors yourself.

The dot moves when I scroll or move the window. Is it a dead pixel?

No. A real pixel fault stays in the same place on the screen no matter what is shown. If the dot moves with the content, it is part of the image; if it can be wiped away, it is dust.

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