UFOZoo

Dead Pixel Test — Free Check Monitor & Screen Defects

Test monitors, laptops, phones, and tablets for dead pixels. Display full-screen solid colors to detect stuck pixels and screen defects. 100% private.

Features

  • ✓Full-screen solid color display — 8 colors (white, black, red, green, blue, yellow, cyan, magenta) to expose all pixel defect types
  • ✓Custom color support — test with any color you choose via color picker
  • ✓Dead pixel detection — black dots that never light up, visible on white background
  • ✓Stuck pixel detection — colored dots (red/green/blue) frozen on one color, visible on black background
  • ✓Hot pixel detection — bright white dots that glow permanently
  • ✓Keyboard shortcuts — Space or Arrow keys to cycle colors, Esc to exit full-screen
  • ✓Touch support — tap screen to cycle colors on mobile devices
  • ✓Works on all devices — monitors, laptops, phones, tablets, TVs with web browser
  • ✓No installation required — runs entirely in browser, no software download
  • ✓100% private — all testing happens locally, no data sent to server
  • ✓Automatic pixel defect counter — tap or click on defect locations to mark them, with a running total displayed on screen for warranty documentation purposes
  • ✓Screen information panel — displays physical resolution, CSS resolution, pixel ratio, color depth, refresh rate, HDR status, and aspect ratio for a complete display profile

How to Use

  1. 1Clean your screen with a microfiber cloth — dust and smudges can look like dead pixels
  2. 2Set screen brightness to maximum — defects are easier to spot at full brightness
  3. 3Click 'Start Test' or any color button to enter full-screen mode
  4. 4Cycle through all 8 colors using Space, Arrow keys, or tap on mobile
  5. 5Look carefully for dots that don't match the background color on each screen
  6. 6Mark any defects — dots that persist across multiple colors are real pixel defects
  7. 7Press Esc or click outside to exit full-screen mode
  8. 8Use the red and blue screens specifically to identify stuck sub-pixels — a red dot on the blue screen indicates a red sub-pixel that is stuck on
  9. 9Photograph any confirmed defects with your phone while the test screen is displayed — this creates visual evidence for warranty claims with the manufacturer or retailer

Frequently Asked Questions

What is the difference between dead, stuck, and hot pixels?

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Dead pixels are completely black (all sub-pixels off, transistor failed) and permanent. Stuck pixels show a fixed color (red, green, or blue) because one sub-pixel is locked on — these may be fixable. Hot pixels glow bright white permanently and are usually permanent. All three are classified under ISO 9241-307 defect standards.

Can I fix a stuck pixel?

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Stuck pixels can sometimes be fixed by rapidly cycling colors for 10-30 minutes, which 'massages' the liquid crystal back to normal state. You can do this manually by tapping the screen to cycle through colors. Dead pixels (black) and hot pixels (white) are usually permanent hardware failures.

How many dead pixels are acceptable?

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ISO 9241-307 Class II (most consumer displays) allows up to 2 bright defects, 2 dark defects, and 5 total defects per million pixels. However, manufacturer policies vary: Dell UltraSharp replaces on 1 bright pixel, BenQ has Zero Bright Dot policy, LG requires 5+ defects. Always check your warranty terms.

Does this work on phones and tablets?

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Yes. Open this page on any device with a modern browser. On iOS, the Fullscreen API is restricted, so the tool expands to maximum viewport (100vh) instead. Hide the browser address bar by scrolling or using 'Hide Toolbar' mode for best results.

Why test with 8 colors instead of just black and white?

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Each pixel has 3 sub-pixels (red, green, blue). The 8 colors represent all ON/OFF combinations: white (all ON) finds dead pixels, black (all OFF) finds stuck/hot pixels, and red/green/blue reveal which specific sub-pixel has failed. Yellow/cyan/magenta provide additional contrast for edge cases.

Will this damage my screen?

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No. Displaying solid colors is completely safe and does not cause burn-in or screen damage. Burn-in occurs from static images displayed for hundreds of hours, not from short-term color testing.

Can dead pixels spread to neighboring pixels?

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A single dead pixel does not physically spread. However, additional unrelated pixels can fail over time on the same display. If you notice a cluster growing in one area, it usually indicates panel damage or pressure points, which may worsen.

Is my data sent to a server?

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No. This tool runs entirely in your browser using the Fullscreen API. No screen data, test results, or any information is sent to our servers. Your testing is 100% private.

How do I distinguish between a dead pixel and a piece of dust?

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Dust and smudges on the screen surface move when you gently wipe with a microfiber cloth, while dead pixels remain fixed in the same position regardless of cleaning. Stuck pixels may change color across different test screens (red→green→blue), while dead pixels stay black on all colors. Use the white screen test first — dust appears as a spot that changes when you view from different angles, while a dead pixel looks like a tiny black dot that stays in the exact same position.

What should I do if I find dead pixels on my new monitor?

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First, check your monitor's warranty policy — most manufacturers have specific pixel defect policies. Take photos of each defect against the relevant test color (black dot on white screen, colored dot on black screen). Contact the manufacturer or retailer with your photos and the total defect count. Some brands like Dell UltraSharp and BenQ have zero-tolerance policies for bright pixels within their premium lines. For budget monitors, manufacturers often require 5+ defects before accepting a return. If within the return window, the retailer may accept a return regardless.

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