Dead & stuck pixels
Nine pure colors, edge to edge. A dead pixel stays black, a stuck one stays lit.
1 minGuide
Backlight Bleed Test
Full black in a dark room: light leaking from the edges shows up. 100% in your browser - nothing is uploaded.
30 s1 pattern
Click the preview to run it full screen
Your display
Updates when you move the window to another screen- Resolution
- ---
- device px
- Pixel ratio
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- devicePixelRatio
- Refresh rate
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- measured in this browser
- Color gamut
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- reported by the browser
- HDR
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- standard range
- Orientation
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- current
How to run the backlight bleed test
01Lights off, brightness up
Dim the room completely and set the monitor to 100% brightness for the check.
02Go full black
Start the test and give your eyes a few seconds to adjust to the dark.
03Check edges and corners
From your normal seat, look along every edge for light pushing in.
04Move your head
Bleed stays put. A sheen that shifts as you move is IPS glow, which is normal.
05Repeat at your brightness
Bleed that only shows at 100% in a dark room rarely matters in daily use.
What to look for
- Bright, often yellowish patches that push in from an edge or corner.
- Patches that stay in the same place when you move your head: that is bleed.
- A silvery sheen that shifts or fades with your viewing angle: that is IPS glow.
What counts as a defect
- Bleed that is visible in dark scenes at your normal brightness is worth a return.
- Faint bleed visible only at 100% in a pitch-black room is common on IPS and VA and usually within spec.
- Glow is a property of IPS panels, not a defect, and every unit of the model has it.
What to do next
- Photos exaggerate bleed. For evidence, use a phone in manual mode and match the exposure to what you see.
- Try another unit only if the bleed is clearly worse than typical reviews of the model.
- Do not loosen bezel screws or press on the frame: it voids the warranty and can crack the panel.
Other screen tests
Each one checks a different part of the panel. The guided check runs them all in order.
Uniformity & clouding
Flat greys and white show clouding, dirty-screen effect and tinted zones.
1 minGuide
Banding & gradients
256 equal steps per ramp. A good panel shows them evenly, a weak one clumps them.
1 minGuide
Sharpness & geometry
One-pixel grids, checkerboards and circles expose scaling blur and bad geometry.
1 minGuide
Refresh rate & tearing
Measures the real frame rate in this browser and shows tearing on a moving bar.
30 sGuide
About the backlight bleed test
On an LCD the backlight sits behind the panel, and when the frame presses unevenly on it, light leaks around the edges. Full black in a dark room makes it obvious. The hard part is telling it apart from IPS glow, which is normal, and this guide shows how.
It is one of the tests in the Screen & Monitor Test, which also runs a guided check through every test and ends in an inspection reportfor a return or RMA. Every pattern is drawn on your screen's own pixel grid, 100% in your browser - no upload, no install, no account needed.
Frequently Asked Questions
Bleed is light leaking around the edges of the panel and it stays put when you move your head. IPS glow is a silvery sheen caused by the viewing angle and it shifts, grows or fades as you move. Glow is normal on IPS panels; strong bleed is a defect.
No. OLED pixels make their own light and switch fully off on black, so there is no backlight to leak. On an OLED use the uniformity and burn-in tests instead.
Phone cameras brighten dark scenes automatically, so faint bleed turns into bright blotches in the picture. Lock the exposure or use manual mode so the photo matches what your eyes see.
Safari on iPhone does not allow web pages to go truly full screen. The test fills the whole visible area and hides all controls instead; rotate to landscape, or add the page to your Home Screen, to get the most of the panel in view. iPad and Android support real full screen.
No. Every pattern is drawn locally in your browser, and the inspection report is built and downloaded on your device. Nothing about your screen or your results leaves the browser, and no account is needed.
From the blog
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Backlight Bleed vs. IPS Glow: How to Tell the Difference
Learn how to distinguish fixed backlight bleed from angle-dependent IPS glow, check a monitor in the right conditions, and decide what to document for a return or RMA.
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