Dead Pixel Test
Cycles through 8 solid colors to reveal stuck or dead pixels that stand out against a uniform background.
Screen Test
Detect dead pixels, stuck pixels, backlight bleed, and display issues. Seven fullscreen test modes — 100% free, private, and browser-based.
Photosensitivity warning: Some test modes contain rapidly flashing lights. Do not use the Stuck Pixel Fixer or Response Time Test if you have epilepsy or photosensitivity.
How to Use
- Clean your screen gently to remove dust and fingerprints that could be mistaken for dead pixels.
- Click "Start Test" on any mode below. The test will open in fullscreen (or a full-page overlay on mobile).
- Click, tap, or press the arrow keys to cycle through patterns. Press ESC or the back button to exit.
Gradient Test
Displays smooth color gradients to reveal banding, bit-depth issues, and poor calibration.
Checkerboard Pattern
Black and white checkerboard at three pixel densities to test sharpness, pixel crosstalk, and scaling artifacts.
Backlight Bleed Test
Pure black screen to reveal light leaking from edges and corners on LCD panels.
Color Uniformity Test
Solid grey levels to check for uneven brightness, IPS glow, or color tinting across the panel.
Stuck Pixel Fixer
A rapidly color-cycling square you drag over a stuck pixel. Leave it running for 10-20 minutes to attempt repair.
Response Time Test
Alternates black and white frames at configurable speeds to assess monitor ghosting and response time.
Frequently Asked Questions
What is a dead pixel?
A dead pixel is a permanently dark pixel that receives no power and appears as a black dot on your screen. Unlike stuck pixels which display a fixed color, dead pixels cannot be fixed by software. They appear clearly against bright solid-color backgrounds.
What is a stuck pixel and can it be fixed?
A stuck pixel is a pixel locked to a single color — red, green, blue, or white. Unlike dead pixels, stuck pixels may be repaired. The Stuck Pixel Fixer mode rapidly cycles colors to stimulate and unstick the pixel. Leave the flashing square over the affected area for 10-20 minutes.
How do I test for backlight bleed?
Use the Backlight Bleed test mode. It fills the screen with pure black. In a dark room, look for any light leaking from the edges or corners of your display. Some backlight bleed is normal on LCD panels, but excessive bleed can be distracting during dark scenes.
What does the gradient test reveal?
The gradient test shows smooth black-to-white and color gradients. If you see visible banding (distinct steps instead of a smooth transition), your display may have limited bit depth or poor calibration. A well-calibrated display should show perfectly smooth gradients.
Why does the cursor disappear in fullscreen mode?
The cursor hides automatically after 2 seconds of inactivity so it does not obscure the test pattern. Move your mouse or touch the screen to make it reappear. The HUD (heads-up display) also reappears when you move the mouse.
Does this tool work on mobile devices?
Yes. All test modes support touch — tap to advance, swipe left or right to navigate. The Stuck Pixel Fixer square can be dragged by touch. Fullscreen mode uses the browser Fullscreen API where supported, with a CSS full-overlay fallback on browsers that do not support it.