Dead Pixel Test
Free online dead pixel test with full-screen solid colors, gradients, and gray sweeps. No install.
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What is Dead Pixel Test?
A dead pixel test fills your entire screen with carefully chosen colors so defective pixels stand out. It cycles through pure white, black, red, green, blue, cyan, magenta, and yellow, then steps through gray levels and smooth gradients. On a healthy panel every color looks perfectly uniform; a dot that stays black is a dead pixel, one that glows a single color on every background is stuck, and blotchy gray gradients point to uneven backlighting. This free tester runs entirely in your browser - open it on the device you want to check, go fullscreen, and scan each color for a few seconds.
Key Benefits
- 13 patterns covering solid colors, gray levels, and smooth gradients in one place
- Fullscreen mode with auto-advance cycling so you can step back and watch the whole screen
- Clear classification guide: dead vs stuck pixels and what each pattern reveals
- Keyboard and touch navigation - Space and arrows on desktop, tap on mobile
- Completely client-side and free - works offline once loaded, no sign-up
Common Use Cases
- •Verifying a brand-new monitor, laptop, or TV before the return window closes
- •Documenting pixel defects as evidence for a warranty or exchange claim
- •Checking a used screen before buying second-hand
- •Comparing backlight uniformity between two monitors at the same settings
- •Re-testing a panel after running a pixel-refresh or color-flashing fix
How to Use the Dead Pixel Test
- Prepare the screen: Clean the display, turn off night-light or blue-light filters, and let the panel warm up for a few minutes so colors render accurately.
- Start the test: Click Start Test to begin from white, or pick any pattern from the grid. The tool fills the screen with the selected color and requests fullscreen.
- Scan each color: Let the colors auto-advance or press Space and the arrow keys yourself. A dot that stays black on every color is dead; one that keeps a single color on all backgrounds is stuck.
- Check gradients and exit: Watch the gray sweep and color gradient for uneven patches, backlight bleed, or tint issues, then press Esc to leave the test.
Key Features
- 13 test patterns: 8 solid colors, 3 gray levels, plus gray and full-color gradients
- One-click fullscreen mode with optional auto-advance every 1-5 seconds
- Pattern grid to jump straight into any single color or sweep
- Keyboard shortcuts (Space, arrows, Esc) and touch-friendly tap-to-advance
- Distinguishes stuck pixels from dead pixels and reveals backlight bleed on gradients
- 100% client-side, free, and offline-capable - no sign-up and no uploads
Frequently Asked Questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel no longer lights up at all, so it stays black on every color you display. A stuck pixel keeps showing one color (red, green, or blue) because only one of its subpixels is frozen. Solid red, green, and blue test screens make the difference obvious: a stuck pixel glows on its own color, while a dead one never glows.
Can this tool fix a dead pixel?
No. This tester only helps you find and classify defects. Stuck pixels sometimes recover after a pixel-refresh cycle or by playing a rapid color-flashing video for a while, but truly dead pixels are a hardware fault that needs panel repair or replacement. Use the test results to support a warranty or return claim.
Why do I need gray and gradient patterns if solid colors are enough to find dots?
Solid colors catch individual pixel defects, but gradients reveal panel-wide issues: uneven backlight bleeding, cloudy spots (mura), and color tint shifts that only show up across smooth transitions. A screen can pass every solid color and still look bad in dark scenes, which the gray sweep exposes.
Does the test work on phones and tablets?
Yes. The tester runs in any modern mobile browser. Tap to advance colors and use the on-screen Exit button since keyboards are unavailable. For best results, set the screen brightness high, disable dark mode or blue-light filters, and rotate to the orientation you use most.