Display Test

Display Test: Check Your Screen for Dead Pixels, Color Issues and More

Display Test is a free online tool that helps you check your monitor, laptop screen, phone or TV for common display problems. It shows 12 full-screen test patterns, one at a time. You step through them and look for anything that seems off.

It also shows basic details about your screen, such as resolution, pixel ratio, color depth, refresh rate and color gamut.

What Can You Check With This Display Test?

Each pattern is built to reveal a specific kind of problem:

• Stuck or dead pixels: tiny dots that stay bright or dark when they shouldn’t.
• Backlight bleed: light leaking in from the edges or corners of the screen.
• Uneven color or brightness: patches that look tinted or darker than the rest.
• Color banding: visible steps in what should be a smooth color transition.
• Motion problems: blur, ghosting or stutter when something moves across the screen.
• Distortion: lines that look bent, stretched or uneven.

How to Use the Display Test

1. Open the tool and pick a test from the dropdown, or use the Previous and Next buttons to move through all 12 patterns.
2. Click Full screen, or click the preview area, to fill the whole display.
3. Dim the room lights. Dark patterns show flaws much more clearly in a dim room.
4. Look closely at the screen, including the corners and edges.
5. Press Next to move on to the next pattern.

The counter beside the dropdown (for example, 1 / 12) shows where you are in the sequence.

The 12 Test Patterns Explained

Black

Use this to look for bright stuck pixels and glow in the corners, which can mean backlight bleed. The tool recommends dimming the room lights for this one.

White

A plain white screen makes dark dots (dead pixels), stains, smudges and uneven brightness easier to see.

Gray

A mid-gray screen helps you spot uneven shading, blotchy patches and faint vertical or horizontal lines.

Red, Green and Blue

These show each primary color on its own. Look for dots that don’t change color, patches that look weaker, and tints that shift across the screen.

Gradient

A smooth color transition is the best way to spot banding. If you see clear stripes or steps instead of a gentle blend, your screen may be struggling with fine color changes.

Color Bars

Color bars show several colors side by side, so you can compare how well your screen separates and displays them.

Grayscale Steps

This pattern shows shades from dark to light in distinct steps. Check whether you can tell each step apart, especially the darkest and lightest ones.

Grid

A grid of straight lines helps you notice distortion, uneven spacing or lines that look soft or crooked.

Checkerboard

Alternating squares make it easy to check sharpness and spot any pixel-level irregularities.

Motion

This pattern is for checking how your screen handles movement. Watch for blur, trailing images or choppy motion.

Understanding the Screen Information

Below the test area, the tool shows six details about your display:

Detail	What it means
Screen resolution	The pixel dimensions of your screen as reported by your browser
Window size	The size of your current browser window
Pixel ratio	How many physical pixels are used for each software pixel (for example, 1.21x)
Color depth	The number of bits used for color, such as 24-bit
Refresh rate	An estimate of how many times per second your screen updates, such as ≈ 60 Hz
Color gamut	The range of colors your display is reported to support, such as sRGB

The resolution and refresh rate are estimates reported by your browser. They may not exactly match your hardware’s official specifications.

Tips for Better Results

• Use full screen. Browser menus and tabs can distract you and hide the edges of the screen.
• Dim the room. Dark and gray patterns show backlight bleed and uneven shading much more clearly in low light.
• Clean your screen first. A speck of dust or a fingerprint can look like a dead pixel. Wipe the screen gently with a soft, dry cloth before you test.
• Look at the edges and corners. Problems often show up there first.
• Test every color. A pixel might look fine on white but stand out on red, green or blue.
• Test at your normal brightness. Then try again at a higher or lower setting to see if the problem changes.

When Is a Display Test Useful?

• Buying a used or refurbished screen: check it before you pay.
• Unboxing a new monitor, laptop or phone: find problems early, while returns and exchanges are easier.
• Calibrating or comparing screens: see how two displays handle the same pattern.
• Troubleshooting: find out whether a strange mark or color shift is a screen problem or a software issue.
• Checking an older screen: see whether it has developed new flaws over time.

Frequently Asked Questions

What’s the difference between a stuck pixel and a dead pixel?

A stuck pixel stays lit in one color, so it shows up as a bright dot, often on a black screen. A dead pixel stays dark and is easiest to see on a white screen.

Is a faint glow in the corners on the black screen normal?

A small amount of glow can appear on some screens when the room is dark. The tool lists glow in the corners as a sign of backlight bleed. If it looks strong or distracting during normal use, you may want to contact the seller or manufacturer.

Why does the tool show a resolution different from my display’s official specs?

The tool reads the values your browser reports. Display scaling and the pixel ratio can change what the browser shows, so the numbers may differ from your hardware specifications.

Why does my refresh rate say “≈ 60 Hz” when my screen supports more?

The tool gives an estimate based on what your browser reports. If you expected a higher number, check your operating system’s display settings to make sure the higher refresh rate is turned on.

How do I leave full screen mode?

Press the Esc key on most keyboards, or use your browser’s standard way of exiting full screen.

Can I use this tool on a phone or TV?

You can use it on any device with a web browser. Use the Full screen button for the best view.

What if I see a problem?

Rule out dirt on the screen first. Then run the same test again, ideally at a different brightness level. If the problem stays in the same spot, it’s likely a real display issue, and your retailer or the manufacturer can advise you on warranty or repair options.