Dead Pixel Test

Press Start fullscreen test and your whole screen turns a single solid colour. Click, tap or press → to step through black, white, red, green, blue, cyan, magenta, yellow, three grays and a custom colour of your choice; ← goes back and Esc leaves. The cursor and captions hide themselves after a moment, so nothing covers the pixels you are inspecting.

On each colour, scan the screen slowly from corner to corner — a magnifying glass or your phone's camera zoom helps on high-density displays. A defect is any dot that doesn't match its surroundings.

What you might find

• Dead pixel — always black. It shows up as a dark dot on the white, red, green and blue screens. The transistor behind it has failed, and software can't bring it back.
• Stuck pixel — one or more subpixels stuck on. It stays red, green, blue or a mix of them, and is easiest to spot on the black screen.
• Hot pixel — stuck fully on, so it is white on black.
• Backlight bleed and clouding — brighter patches near edges and corners on the black and dark-gray screens, typical of LCD and IPS panels. That is a backlight trait, not a pixel fault.
• Uniformity problems — tinted or darker areas on the mid-gray screen, and banding on gradients.

Stuck pixel fixer

The fixer flashes red, green, blue, white and black rapidly inside a small square that you drag over the stuck pixel (or nudge with the arrow keys). Leave it running for 10–20 minutes; the rapid switching sometimes frees a subpixel that is stuck. It works on some stuck pixels and never on dead ones. Because it flashes, you must read and accept a photosensitive epilepsy warning before it starts — look away from the screen while it runs.

Common uses

• Inspect a new monitor, laptop or TV inside the return window
• Check a used or refurbished screen before you buy it
• Confirm a warranty claim: most manufacturers state how many dead or bright pixels they accept
• Judge backlight bleed and IPS glow on a dark room setup
• Clean a screen: the black and white screens show dust and smudges clearly

Example

27-inch monitor, black screen, dark room

One bright green dot near the lower left corner
→ stuck green subpixel

It disappears on the green screen and stays bright on black, red and blue — a stuck pixel, not a dead one. Run the fixer over it for 15 minutes before starting a return.

Limitations

• The test shows colours; your eyes do the finding. Very small defects on 4K and Retina screens are easier to see with magnification.
• iPhone Safari has no fullscreen mode for web pages, so the test covers the browser window instead — rotate to landscape and hide the toolbars by scrolling for the most coverage.
• The fixer can't repair a dead pixel, and success with stuck pixels is hit and miss. Physical methods (pressure, heat) risk damaging the panel.
• Pixel defect policies vary by manufacturer and panel class; check yours before relying on a return.

How do I check my monitor for dead pixels?

Press Start fullscreen test, then step through the colours with a click, tap or the → key. Look closely at the whole screen on each one: a dot that stays black on white and the bright colours is a dead pixel, and a coloured or white dot on the black screen is a stuck or hot pixel. Press Esc when you're done.

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

A dead pixel never lights up, so it is a black dot on every colour except black. A stuck pixel has one or more subpixels permanently on, so it stays red, green, blue or a mix such as yellow or white, and is most visible on a black background. Stuck pixels can sometimes be revived; dead pixels can't.

Can a stuck pixel be fixed?

Sometimes. Running the stuck pixel fixer — rapidly flashing colours over the pixel — for 10 to 20 minutes frees some stuck subpixels. If it doesn't work after a few attempts the pixel is likely permanent. Dead pixels caused by a failed transistor can't be fixed by software at all.

Is the stuck pixel fixer safe?

For the screen, yes — it only changes colours. For people, the flashing can trigger seizures in those with photosensitive epilepsy, which is why the tool asks you to accept a warning first. Keep the square small, look away while it runs, and don't use it if anyone nearby is sensitive to flashing light.

How many dead pixels are acceptable on a new monitor?

It depends on the manufacturer's pixel policy, which is often based on the ISO 9241-307 panel classes. Many brands only replace a monitor once it has several defects, or a bright pixel near the centre; some premium lines promise zero bright pixels. Check the warranty terms for your model and test as soon as it arrives.

Does this dead pixel test work on phones, tablets and TVs?

Yes — anything with a browser. On Android, iPad and desktop browsers the test goes truly fullscreen. On iPhone, Safari doesn't allow fullscreen web pages, so the colours fill the browser window instead. On a smart TV, open the page in the TV's browser or cast a fullscreen browser tab.

How do I check for backlight bleed?

Turn the room lights off, set your brightness to what you normally use, and open the black screen. Brighter patches along the edges or in the corners are backlight bleed or IPS glow. The dark-gray screen shows clouding (uneven blotches) more clearly. Some bleed is normal on LCD panels; OLED screens have none.