Runs in your browser: nothing you enter or choose is uploaded.

This dead pixel test fills your whole screen with one solid color at a time: black, white, red, green, blue and gray, then a fine checker pattern. A pixel that doesn’t match the color around it stands out, so you can spot dead and stuck pixels in a minute or two.

It works on phones, laptops, monitors and smart TVs with a web browser, and nothing is uploaded.

How to use the dead pixel test

Wipe the screen with a soft, lint-free cloth first. Dust looks a lot like a dead pixel on a white screen.
Set the screen to full brightness, and dim the room if you can.
Select Start full-screen test. The screen turns black.
Look across the whole screen slowly, corner to corner. Then click, tap, or press Space or → for the next color. ← goes back.
After the checker pattern, one more tap finishes the test. You can press Esc at any time to stop.
Found a dot? Note where it is and which colors show it. A photo of the screen helps if you need to return it.

A short hint appears at the bottom of the screen and hides itself after a few seconds, so it doesn’t cover any pixels. Move the mouse to bring it back.

Dead pixels vs stuck pixels

Every pixel on an LCD screen is made of three subpixels: red, green and blue. Apple explains that occasionally a transistor doesn’t work perfectly, so a subpixel stays off (dark) or on (bright). Dell uses these names:

Type	What it looks like	Easiest color to spot it on	Can it be fixed?
Dead (dark) pixel	A black dot that never lights up	White, or any bright color	No. Dell says no software can bring it back; the panel has to be replaced
Stuck (bright) pixel	A white dot that’s always lit	Black	Sometimes, maybe. See the pixel fixer below
Stuck subpixel	A red, green or blue dot	Black, or the other two colors	Sometimes, maybe
Dust or debris	A soft, irregular speck	White	Wipe the glass. Apple says debris trapped inside needs a service provider

The checker pattern is a different kind of check. Up close it should look like an even, fine gray texture. Blurry patches or wavy lines can mean the screen isn’t running at its native resolution.

How to check a new or used screen

Run the dead pixel test as soon as you unpack a new device, while you’re still inside the return window. For a used device, run it before you hand over any money.

Phone or tablet

Open this page in the phone’s browser and start the test. Tap to move through the colors, and turn the phone so you can see every edge, including any notch or camera cutout. If your browser can’t switch to full screen, the test fills the browser window instead: scroll so the address bar shrinks, or check the edges separately. More phone help is on our Android hub and iPhone hub.

Laptop

Run the test on the built-in screen with the brightness turned up. On the black screen, also look at the edges for light leaking in, which shows most in a dark room. On gray, look for blotches or bands. Moving to a new Windows PC? See how to move your files to a new Windows 11 PC once the screen checks out.

Monitor

If you have more than one screen, drag the browser window onto the monitor you want to test before you start. The full-screen test then fills that monitor. Use the monitor’s native resolution: in Windows 11, Microsoft says to go to Settings → System → Display and choose the option marked (Recommended) under Display resolution.

TV

Open this page in the TV’s own web browser, if it has one. Otherwise connect a laptop with an HDMI cable, move the browser window to the TV and start the test there. Stand at your normal viewing distance first, then get closer to check anything you spot.

What the screen info means

Next to the test you’ll see your screen size in CSS pixels, the pixel ratio and an estimate of the real (physical) pixels. Websites measure in CSS pixels; a high-resolution screen uses several physical pixels for each one. MDN describes the pixel ratio as the number of physical pixels per CSS pixel, and it changes when you zoom the page. Multiply the two and you get the physical resolution, so a Windows laptop at 125% scaling might show 1536 × 864 CSS pixels and a ratio of 1.25, which works out to 1920 × 1080. Set the browser zoom to 100% for the best estimate.

Returns, warranties and pixel policies

Manufacturers don’t all treat a few bad pixels as a fault. Check your product’s own policy before you ask for a replacement:

Dell publishes display pixel guidelines. Its Premium Panel Exchange covers series such as UltraSharp and Dell Pro P monitors, and Dell laptops with HD+ resolution or higher, with zero tolerance for bright pixels. It only counts pixels that are permanently on or off and visible at normal viewing distance.
Apple says pixel anomalies can occur in a small percentage of LCD panels and doesn’t publish a number. It asks you to take the device to an Apple Store, an Apple Authorized Service Provider or an Independent Repair Provider to have it examined.
Other brands usually cover this in the warranty or a separate pixel policy. Search the maker’s support site for the model’s warranty terms.

The US Federal Trade Commission’s advice applies too: read the warranty and the store’s return policy, keep your receipt, and contact the seller first, then the manufacturer. A store’s own return window can be the easiest route for a brand-new screen, so test early. Before sending a laptop for repair, back up your Windows PC.

Can you fix a stuck pixel?

Maybe, but don’t count on it. The tool’s Pixel fixer flashes a small square through red, green, blue, white and black very fast. You drag the square over the stuck pixel (or move it with the arrow keys) and leave it running for a while. This is a long-standing home remedy for stuck pixels, but no manufacturer we cite promises it works, and Dell is clear that a dead pixel can’t be revived by any software.

The pixel fixer flashes rapidly. Flashing light can trigger seizures in people with photosensitive epilepsy, and can cause migraines or nausea. The W3C’s accessibility guidelines warn against anything that flashes more than three times a second.

Don’t use it if you or anyone who can see the screen is sensitive to flashing light. Don’t watch it: start it, look away, and come back later. It only starts after you tick the warning box, and if your device is set to reduce motion it stays paused until you start it yourself.

If the pixel is still there afterwards, it’s time for the warranty or return route.

If the test doesn’t work

Windows 11: if the screen doesn’t go full screen, the test still fills the browser window. Press Esc to exit. If text looks blurry on the checker pattern, check that Display resolution is set to the recommended option.
Mac: the test works in Safari, Chrome and Firefox. If you use more than one display, move the window to the screen you want to test first. More help is on our Mac hub.
iPhone: if the browser bars stay visible, check the strips they cover separately by scrolling, or turn the phone sideways.
Android and Galaxy: use the back gesture or button to leave full screen if you can’t tap through to the end. If taps don’t change the color, tap the middle of the screen rather than the edges.
Any device: turn off night light, blue light filters or reading modes while testing. They tint the colors, which makes stuck subpixels harder to see.

Privacy

The dead pixel test runs in your browser. It reads your screen size and pixel ratio to show the info panel, and nothing is sent or stored.

Related free tool: our webcam test.

FAQ

How do I test my screen for dead pixels?

Clean the screen, turn brightness up, and start the full-screen test. Look over each solid color carefully. A black dot on white is a dead pixel; a bright or colored dot on black is a stuck pixel.

What’s the difference between a dead pixel and a stuck pixel?

A dead pixel stays off and looks black. A stuck pixel stays on, showing white, red, green or blue. Dead pixels can’t be fixed; stuck pixels sometimes respond to flashing colors, but there’s no guarantee.

Is one dead pixel covered by warranty?

It depends on the brand and model. Dell, for example, has zero tolerance for bright pixels on UltraSharp and Dell Pro P monitors. Apple asks you to bring the device in for examination. Check the product’s pixel policy and the store’s return window.

Can a dead pixel spread?

A dead pixel is usually a fault in that one spot. If you see more appearing over time, or lines and patches, get the screen checked under warranty.

Does the dead pixel test work on a TV?

Yes, if the TV has a web browser, or if you connect a laptop with HDMI and run the test on the TV screen.

Dead Pixel Test (Full-Screen Colors for Any Screen)