How to Check for Dead Pixels on Your Screen

Guides · Web · Updated 2026

A tiny black dot that stays put no matter what you’re watching can be maddening. That’s a dead pixel — and on a new monitor or smartphone, it’s a genuine reason for a warranty claim. The problem is, dead and stuck pixels aren’t always obvious unless you run a proper screen test. This guide explains how to check any display using a full‑screen colour cycling tool that requires no downloads — just a browser.

Dead pixel vs. stuck pixel: what’s the difference?

A dead pixel is a pixel that no longer lights up at all. It appears as a permanent black spot on every solid colour. A stuck pixel, on the other hand, is a sub‑pixel (red, green, or blue) that remains constantly on. For example, a stuck red pixel is visible on a white background but invisible on a red one. Knowing the difference helps you decide whether a display is truly faulty.

Dead pixel: black on white, black on red, black on every colour.
Stuck pixel: appears coloured on black or white, but blends in on certain colours.

Step-by-step: test your screen for dead and stuck pixels

Open the Screen Test tool on the device you want to inspect.
Click Start Fullscreen Test and grant fullscreen permission when prompted. The tool will fill the entire screen with white.
Click anywhere on the screen to cycle through the colours: white → black → red → green → blue → gray gradient.
On each colour, scan the screen slowly from top to bottom. Look for any pixel that stands out — either a black dot (dead) or a bright dot of a different colour (stuck).
Press the Escape key to exit the test when you’re done.

💡 Tip: For the most accurate inspection, clean your screen first — dust or a tiny speck of dirt can look exactly like a dead pixel. Use a micro‑fibre cloth and a magnifying app or a jeweller’s loupe if you want to be 100% certain.

What to do if you find a dead pixel

Manufacturers often have a “dead pixel policy” — some allow up to 2–3 dead pixels before accepting a return. If your display is under warranty and has a clearly visible dead pixel, contact support immediately. Stuck pixels can sometimes be revived by gently massaging the area with a soft cloth (use a pixel‑fixing video first), but be careful not to damage the screen further.

Frequently Asked Questions

Can a dead pixel fix itself?

Rarely, but sometimes a pixel that appears dead is actually just a software or driver glitch. Restart your device and run the test again. If the dot persists, it’s a hardware issue.

Will this test work on a phone screen?

Absolutely. Open the tool in your phone’s browser, start the fullscreen mode, and cycle colours just as you would on a monitor. It’s a great habit to run this test within a few days of buying a new phone.

Why is a gray gradient included?

A gray gradient helps reveal banding or uneven backlighting, which can indicate a developing screen fault, not just dead pixels.

How often should I test my screen?

Right after buying a new device and again before the warranty expires. Beyond that, testing once every 6–12 months is enough unless you notice something odd.

Is it free and private?

Yes — the tool runs entirely in your browser, free, with no sign‑up and nothing uploaded to a server.

Try the Screen Test