Dead Pixel Test
Free full-screen dead pixel test for monitors, laptops, phones, and TVs. Cycle solid colours to find dead, stuck, or hot pixels, then try the stuck pixel fixer.
Pick a colour and go full screen. Then click, tap, press Space, or use the arrow keys to cycle through white, black, red, green, blue, cyan, magenta, yellow, and gray. Look carefully across the whole panel for dots that do not match. Exit with Esc, a double tap, or the Exit button in the top-right corner.
Full screen uses the browser's Fullscreen API. On iPhone and iPad, Safari does not support it, so the test covers the viewport instead; the address bar may stay visible.
Clean the screen first: dust and fingerprints look exactly like dead pixels on a white background. Test at your normal brightness, then again at maximum.
Stuck pixel fixer
This flashes rapidly changing random colours inside a small square. Drag the square over the stuck pixel and leave it running. Rapid cycling can free a sub-pixel that is stuck on a single colour; it does nothing for a dead (black) pixel. Results are not guaranteed, but 10 to 30 minutes is a reasonable first try.
You will be asked to confirm before it starts. Drag the flashing square with the mouse or a finger. Stop at any time with the button on the bar, or press Esc.
Dead, stuck, and hot pixels
A modern screen is a grid of millions of pixels, each made of red, green, and blue sub-pixels driven by their own transistors. When a transistor fails, the pixel stops responding. A dead pixel is permanently off, so it shows as a black dot on white, red, green, and every other colour. It is easiest to spot on the white screen. A stuck pixel has a sub-pixel that is permanently on, so it appears as a red, green, blue, or other coloured dot on the black screen and blends in on the colour it is stuck on; cycling through red, green, and blue individually shows you which sub-pixel is at fault. A hot pixel is all three sub-pixels stuck on, so it glows white on black. Dead pixels are physical failures; stuck pixels are sometimes electrical and occasionally recover with the fixer above.
Defects can also appear as clusters or as a bright spot that is larger than one pixel. On an LCD, a bright blotch that is visible on dark screens is usually a pressure mark or a backlight bleed problem rather than a pixel defect; on an OLED, an uneven patch is usually retention or burn-in.
Warranty and return policies
Manufacturers grade panels by how many defects they will tolerate, broadly following the ISO 9241-307 classes. A typical consumer monitor is sold as class II, which permits a handful of defective pixels per million before the panel is considered faulty, so a single dead pixel often does not qualify for a warranty replacement. The exact thresholds vary by brand, by model line, and by whether the defect is bright or dark, so treat any specific number you read online as a guide and check the policy that came with your device. The practical advice is simple: run this test on the day a new screen arrives. Retailer return windows usually let you exchange for any reason, which is a far easier path than arguing about pixel counts later.
Checking an OLED for burn-in
OLED pixels emit their own light and age with use, so static elements such as a taskbar, news ticker, or game HUD can leave a faint permanent shadow. The gray swatches are the best way to see it: on a uniform mid-gray, look for ghosted shapes, colour tints in the corners, or vertical bands. Dark gray reveals uneven brightness; light gray reveals colour shifts. Temporary image retention fades after a few minutes of varied content and is normal; a shape that is still there the next day is burn-in. Most OLED TVs and monitors run an automatic pixel refresh cycle when powered off, and a manual refresh option in the settings can reduce mild cases.
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 colour; it is a broken transistor and cannot be fixed by software. A stuck pixel is lit but frozen on one colour (usually red, green, or blue) because one of its sub-pixels is stuck open; these sometimes recover with the flashing fixer above or gentle massage. A hot pixel is always white, and is the sub-pixel equivalent of all three being stuck on.
How many dead pixels are needed for a warranty replacement?
It depends on the manufacturer and the panel class. Most consumer monitors follow a policy in the spirit of the ISO 9241-307 pixel-defect classes, which allow a small number of defects per million pixels on a standard "class II" panel, so a single dead pixel is often not covered. Premium models, some laptop makers, and many retailers offer zero-bright-dot or zero-dead-pixel guarantees for a limited period after purchase. Check the exact policy for your model, and test within the return window while you can still simply return it.
Can I fix a dead pixel?
A truly dead (black) pixel almost never recovers. A stuck (coloured) pixel sometimes does. Run the fixer over it for 10 to 30 minutes, and if that fails, some people report success by very gently pressing the spot through a soft cloth while the screen cycles colours. Never press hard on an LCD or OLED; you can create more damage than you fix. If it is a new device, exchange it instead.
Why does the full-screen mode not work on my iPhone?
iOS Safari does not allow web pages to put an element into full screen. This page falls back to a fixed overlay that covers the whole viewport; the browser toolbar may remain visible. For a complete check on an iPhone, add the page to your home screen, or scroll slightly so Safari hides its toolbar before starting.
How do I check an OLED for burn-in?
Use the gray swatches. Burn-in shows as faint ghost images (a taskbar, a channel logo, a browser tab bar) that remain visible on a uniform mid-gray screen. On a dark gray you can also see uneven brightness bands. Pixel refresh routines built into most OLED TVs and monitors reduce mild retention; permanent burn-in cannot be reversed.
Is a single stuck pixel a reason to return a monitor?
That is up to you and the seller's policy. Stuck pixels near the centre of the screen are far more noticeable than ones at the edge, and a bright pixel is more distracting than a dark one. If you are inside a retailer return window, exchanging is easy; outside it, most manufacturers will not replace a panel for one defect unless it came with a zero-defect promise.
Last updated 2026-09-15. Everything on this page runs in your browser. Nothing you type or upload leaves your device.