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Backlight Bleed Test

Pure-black fullscreen reveals IPS bleed in the corners.

Press F for fullscreen

Look for light leaks in the corners

About Backlight Bleed Test

Backlight bleed shows up as cloudy bright zones in the corners or edges of an LCD panel on a black screen. Open this page in a dark room, hit fullscreen, and look at every edge. IPS panels often bleed slightly; a heavy bleed pattern across one side may be a defect.

IPS Glow and Backlight Bleed Diagnosis

All IPS panels exhibit some degree of backlight bleed — light leaking through the LCD at the edges and corners when displaying black. This tool fills your screen with pure black so you can assess the severity in a dark room. Minor bleed in the corners is normal and does not affect typical content viewing. Heavy bleeding along one edge or a single bright corner may indicate panel stress, a manufacturing defect, or over-tightened VESA mount screws. Professional reviewers use this test as the first step in any monitor evaluation, and consumers should run it before accepting a new display.

Panel Defect vs Normal IPS Behavior

Distinguishing between acceptable IPS glow and a defective panel requires a systematic check. Open this tool fullscreen in a completely dark room and let your eyes adjust for 60 seconds. Walk your gaze around every edge and corner. Normal IPS glow appears as a soft, diffuse brightness in multiple corners that shifts when you change viewing angle. A defect appears as a concentrated bright spot, a band of light along one edge, or a cloud that does not shift with angle. Document the pattern with a photo in manual exposure mode — if the bright area blows out while the rest of the screen reads as black, it is likely a defect worth returning.

Pre-Purchase Monitor Comparison Tool

When comparing two monitors side by side, run the backlight bleed test on both simultaneously. The side-by-side comparison reveals which panel has better uniformity and less light leakage. This is especially useful for multi-monitor setups where panel consistency matters — mismatched bleed patterns become distracting when both screens display dark content. Video editors, programmers, and traders who run multiple monitors benefit from selecting panels with similar bleed characteristics. Use this tool as the final acceptance test before deciding which monitor to keep.

How to use it

  1. 01

    Dim the room

    Backlight bleed is invisible with the lights on. Kill the overhead and let your eyes adjust.

  2. 02

    Press F to fullscreen

    The page fills the panel in pure black so any leakage stands out.

  3. 03

    Inspect every edge

    Walk your eye around the perimeter and across the corners. A small amount of bleed is normal on IPS; a single bright corner or a band along one edge is a defect.

  4. 04

    Download the current view as a PNG

    Click the download icon in the top-right toolbar — it sits between the settings gear and the fullscreen button. We detect your display's physical pixel count (screen resolution × device pixel ratio) and rasterize the current configuration into a Retina-sharp PNG. The file lands in your browser's default downloads folder; to save straight to the Desktop, enable 'Ask where to save each file' in your browser settings. The filename includes the resolution so you can keep multiple variants side by side.

Frequently asked

The shortest path between you and the answer.

Is this tool free?

Yes. Every ScreenTools.co tool is free, with no account, no paywall, and no install.

Does it work on mobile?

Yes. Layouts adapt to phone and tablet screens. Mobile Safari restricts true fullscreen, but the page fills the viewport and you can add the page to your Home Screen for an app-like experience.

Does it work offline?

Once a tool's page has loaded once, the runtime is local. A few tools that fetch fonts or icons need the first hit online; after that, refresh works offline.

Does this collect my data?

No personal data leaves your browser. The site has lightweight, privacy-respecting analytics for aggregate counts (which tool was opened) and nothing else.

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