Monitor Test
Full-screen test patterns for your monitor — gradients, banding, sharpness, contrast, and backlight bleed.
Seven full-screen patterns that reveal what solid colors can't — banding in gradients, crushed contrast steps, scaling blur, crooked geometry, backlight bleed, and uneven panels. For dead or stuck pixels, use the dedicated dead pixel test.
Examples
Check for banding
Input
Grayscale gradient
Output
Smooth ramp = good, stripes = banding
Verify native resolution
Input
1px checkerboard
Output
Uniform gray = correct scaling
Inspect backlight bleed
Input
Black pattern in a dark room
Output
Even black = healthy panel
About this tool
This free online monitor test runs seven full-screen test patterns that reveal panel problems solid colors can't: color banding in gradients, crushed contrast steps, sharpness and scaling blur, crooked geometry, backlight bleed, and uneven uniformity. Everything is drawn in your browser with no install.
How to use
- Click a pattern tile (or start from the first) to go full screen.
- Read the hint for what to look for, then inspect the screen.
- Click or press → to move through all seven patterns.
- Press Esc to exit at any time.
Common uses
Inspecting a new or second-hand monitor within the return window, checking a panel after a repair, verifying your display runs at native resolution, or judging whether backlight bleed is bad enough to exchange. Pair it with the dead pixel test for individual pixels and the FPS test to confirm the refresh rate.
Frequently asked questions
What does this monitor test check?
Seven full-screen patterns, each targeting a different fault: grayscale and color gradients for banding, contrast steps for crushed shadows and highlights, a 1-pixel checkerboard for sharpness and scaling problems, a grid for geometry, pure black for backlight bleed, and 50% gray for panel uniformity.
How is this different from the dead pixel test?
The dead pixel test cycles solid colors to make individual defective pixels stand out. This test looks at panel-level quality — how smoothly it renders gradients, whether contrast steps survive, and whether the backlight is even. For a full inspection, run both.
What is color banding and what causes it?
Banding is when a smooth gradient shows visible stripes instead of a seamless ramp. It comes from limited color depth (6-bit panels), aggressive monitor processing, or the graphics driver outputting fewer bits than the panel supports. Some banding on a gradient test is common on budget panels.
The 1px checkerboard looks blurry or shows patterns — what does that mean?
At the panel's native resolution, a 1-pixel checkerboard should look like flat, uniform gray. Blur or shimmering moiré usually means the monitor isn't running at native resolution, or OS display scaling is resampling the image. Check your resolution settings first.
Is backlight bleed on the black screen a defect?
Some glow along edges or corners is normal for LCD panels — it's the nature of an always-on backlight. Strong, uneven blotches visible in a dim room are worth a return or exchange while you're within the window. OLED screens should show perfect black with no bleed at all.
I can't tell the darkest contrast steps apart — is the monitor broken?
Not necessarily. Being unable to distinguish the last one or two steps near black or white is common and often fixable: check the monitor's brightness/contrast settings, disable dynamic contrast, and make sure the room isn't too bright. If large groups of steps merge, the contrast setting is badly off.
Is anything installed or uploaded?
No. The patterns are drawn entirely in your browser with CSS. Nothing is installed, saved, or sent anywhere.
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