How to check a screen for dead pixels

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As you read this, you are looking at more than just the text on the screen.  What you are actually viewing are pixels.  Those are the extremely tiny dots that make up what is being displayed on your screen.  Depending on your screen, there could be many thousands of them or even more than a million.

dead pixel

How many pixels are actually on a screen?  Here’s how to figure it out.

Do a right-click on an open area of your desktop, and choose “Screen resolution” (if you are on XP or Vista, go to Control Panel and open the Display settings).



The screen resolution will read something like 1024 x 768 or 1280 x 1024 or something similar.  If you multiply those two numbers, that gives you the total number of pixels on your screen.  In my case, I use two 19 inch monitors and each one is 1280 x 1024, so each one has 1,310,720 pixels at that resolution.  To give you an idea of how tiny they are, that means my monitors have over 7000 pixels per square inch.  That’s pretty small!

So now you know what a pixel is, and that you have lots of them.  But don’t get too attached, because they sometimes unfortunately die.  In many cases, a single pixel can die even though it is surrounded on all sides by pixels that are still completely alive.

dead pixel

A pixel can die from a variety of causes because they are fairly sensitive – being touched with too much pressure, being dropped, even a pesky dust particle can be a problem for a pixel.  And if your screen has a wallpaper that uses a mix of colors and patterns, a dead pixel might not even be noticeable.  Even if you do notice a dead one, or a few, you might make the deliberate decision that it’s not worth it to replace the whole monitor since it still works okay otherwise.

But when you are buying a monitor – or even more importantly, when you are buying a laptop – you want to check the screen and see that all of the pixels are alive and kicking.

I used to check for dead pixels by going into the settings and changing the Windows background to all white, then telling the computer to not show the icons on the desktop.  That procedure was okay, but I have since discovered a better way.

There is a website that is designed for this, and it is very simple to use.  It is called “Do I Have a Dead Pixel?” (DoIHaveADeadPixel.com).

When you go there, you will see how easy it is.  You just choose the background color you want to use:

dead pixel checker

Then hit the F11 key on the keyboard so that the web browser is expanded to full screen.  Look closely at the screen for anything that doesn’t seem to belong there, then when you’re finished just tap the F11 once again to bring back the browser toolbars and menus.

This site is especially handy if you are buying a used monitor or a used laptop, to make sure the screen is in good working condition.  And if you order a display online, you should check it for any dead pixels immediately when it gets delivered to you.  Some manufacturers allow up to a certain number of dead pixels as “acceptable” and would not consider a display within those limits to be defective.  However, if you catch it immediately upon receipt, you can use the retailer’s standard return policy to get a different one.  Return policies vary but are usually 14 to 30 days.

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