Online Monitor Test: Find dead pixels and backlight bleed

If your screen looks off, you can check it here in seconds. When you notice dead pixels, bright stuck pixels, uneven brightness, backlight bleed near the edges, or strange color patches, this test helps confirm it. Run the patterns directly in your browser to inspect screen uniformity, color accuracy, and panel issues before assuming the monitor or laptop display is defective.

Pick a test to begin

Don't miss a defect: How to test properly

A quick glance isn't enough to find subtle panel issues. Follow these steps to ensure you’re seeing everything.

Monitor testing: What you need to know

Screen defects are easy to miss during normal use. This guide explains how to use our patterns to catch hardware issues before they become a permanent problem.

What is this test for?

Standard apps and wallpapers are great at hiding defects. Our tool uses specifically engineered fullscreen patterns to "stress test" your pixels. It forces every part of your panel to show its true colors, making it impossible for dead pixels or backlight issues to stay hidden.

Since it runs entirely in your browser, you don't have to risk downloading weird executables just to check your screen.

How it helps you spot defects

The logic is simple: by displaying perfectly uniform colors and gradients, we remove all "visual noise." If your monitor has a hardware flaw, it will stick out like a sore thumb against our solid backgrounds.

Whether it’s a tiny black dot (dead pixel) or a weird glowing patch in the corner (backlight bleed), these patterns make it obvious.

When should you use this?

Always run these tests the moment you unbox a new monitor or laptop. Many manufacturers have a "zero dead pixel" policy only for the first few days. Testing immediately ensures you can get a replacement or refund while the warranty is still fresh.

It’s also great for used gear, helping you verify that "Grade A" listing is actually telling the truth.

Does it work on my screen?

Yes. Whether you have a $2,000 OLED gaming display, an ultrawide productivity beast, or a standard laptop screen, these tests work the same. It is compatible with Windows, Mac, and Linux because it relies on web standards, not system drivers.

It’s completely safe—we just show you colors; we don't change any of your hardware settings.

What these patterns reveal

Each test is a targeted check for specific hardware flaws. Here is how to interpret what you see on your screen.

Dead & Stuck Pixels

Cycle through red, green, blue, and white. A dead pixel is a tiny black speck that never turns on. A stuck pixel stays one bright color (usually red or green) even when the background changes.

Color Banding

Gradients should be buttery smooth. If you see visible "steps" or lines instead of a clean transition, your monitor might be struggling with bit-depth or have poor internal processing.

Shadow & Highlight Detail

This test reveals "black crush." You should be able to distinguish between very dark gray and pure black. If the dark boxes all look the same, you're losing detail in movies and games.

Bleed & Uniformity

Check a pure black screen in a dark room. Bright "glow" near the corners is backlight bleed. Patchy, cloud-like areas in the middle indicate poor panel uniformity.

Text Clarity

If text looks "fuzzy" or has a weird shadow, your sharpness setting is likely too high or your resolution isn't native. Use this to get your font rendering pixel-perfect.

Color Shifting

Move your head from side to side. If the colors wash out or change tint, your panel has limited viewing angles. This is common on TN panels but shouldn't happen much on IPS screens.

Ghosting & Trails

Watch the moving objects. If you see a "smear" or a faint trail following the shape, that's ghosting. It usually means the pixels can't change color fast enough for high-speed motion.

Hz Verification

Many 144Hz monitors ship defaulted to 60Hz. This counter shows what your browser is actually seeing. If it doesn't match your monitor's box, check your Windows or Mac display settings.

Frequently Asked Questions

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

A **dead pixel** is a pixel that remains unlit (black) at all times. This is typically a hardware defect that cannot be fixed. A **stuck pixel** is a pixel that is permanently stuck on one color (usually red, green, or blue) because one of its sub-pixels is always on. Stuck pixels can sometimes be fixed with software tools.

How do I test for backlight bleed?

The best way to test for backlight bleed is to use the "Screen Uniformity" test. Select the black or dark gray color pattern, make your room as dark as possible, and increase your monitor's brightness. Look for patches of light "bleeding" in from the edges of the screen. This is most common on LCD/LED displays.

Is this test compatible with OLED displays?

Yes, all tests except the "Screen Uniformity" test for backlight bleed are fully compatible with OLED displays. Since OLED pixels produce their own light, they do not have a backlight and therefore cannot suffer from backlight bleed or clouding. The dead pixel and color tests are still very useful for OLED screens.

How do I use this online monitor test?

It's simple. Use the buttons to cycle through the different test patterns. We recommend going full-screen (press F11) in a dark room. Carefully inspect the screen during each color test (Red, Green, Blue, White, Black) to find any dead or stuck pixels. Use the other patterns to check for uniformity, ghosting, and color banding.

Can this tool fix a stuck pixel?

This tool is primarily for *testing* and *finding* pixels. However, some users have success fixing stuck pixels by rapidly cycling through different colors. You can try our "Stuck Pixel Fixer" tool, which flashes high-contrast colors to try and "unstick" the pixel. This is not guaranteed to work and has no effect on dead pixels.

What is screen ghosting or motion blur?

Ghosting (or motion blur) is a trail or "ghost" image left behind by moving objects on a screen. It's caused by a monitor's slow response time. Our "Ghosting Test" (often a UFO or moving box pattern) is designed to make this effect obvious. A high-refresh-rate monitor with a fast response time will show a much clearer moving image.

Is this monitor test tool safe and private?

Yes, 100%. This tool is a simple web page that runs entirely in your browser. It does not install any software, and no data about your monitor or system is sent to our servers. It's completely safe and private to use.

Not sure what the result means?

The tester shows what your device is reporting. The guide explains what the result actually indicates and what you should try before replacing the hardware.

Read the troubleshooting guide