Backlight Bleed Test
Fill your screen with black and near-black slides to reveal light leaking from the edges of an LCD panel — bleed, clouding and IPS glow.
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Recommended · 5 patterns · 5s each
Starts with the recommended setup. Nothing to configure.
Advanced timing
Change how long each pattern stays on screen, or turn automatic advance off.
Free · No download · No sign-up · Runs locally in your browser
For a fair result
- 1. Turn the room lights off — bleed is invisible in a bright room.
- 2. Set brightness to the level you actually use, not maximum.
- 3. Sit at your normal viewing distance, straight on.
- 4. Move your head side to side: glow that shifts is IPS glow, glow that stays put is backlight bleed.
Viewing angle check
With a black screen in a dark room, move your head left, right, up and down. Does the bright area noticeably change as your viewing angle changes?
Yes — it shifts and fades as I move ›
The effect may be related to viewing angle rather than a leak. Panel glow is a property of the technology — it is present on essentially every unit of the same model, and it disappears the moment you sit straight on at your normal distance. Judge it from your actual seating position, not from 40 cm off to one side.
No — it stays exactly where it is ›
The bright area appears more fixed. Continue checking for edge bleed or clouding: step through black, 1%, 2%, 5% and 10% gray and note at which level it stops being visible. Bleed still obvious at 5% on a new device is worth documenting for an exchange.
Still not sure which one you are looking at? Run the diagnosis →
Backlight bleed vs IPS glow
Both look like brightness leaking into a dark screen, but they are different things. Backlight bleed is light physically escaping between the panel and its frame, usually as bright patches along edges and in corners. It stays in the same place no matter where you sit. IPS glow is an optical property of IPS panels: a silvery or warm sheen, strongest toward corners, that moves and fades as you change your viewing angle or distance.
Almost every LCD shows some of one or both — panels are backlit, and perfect sealing is rare. Judge severity by whether you can see it during real content in your normal room lighting, not by a worst-case photo taken at maximum brightness in the dark.
When is bleed bad enough to act on?
There is no industry standard for acceptable bleed, so retailer return windows are your practical tool. A reasonable bar: if bleed is clearly visible in dark movie scenes at your normal brightness, an exchange is justified — panel lottery means the replacement may well be better. Note that OLED screens cannot have backlight bleed at all, since each pixel emits its own light; if you see glow on an OLED, run the uniformity test instead.
Found something worth reporting? Document it with a screen test report and photograph the screen in a dark room from your viewing position.
What this test checks
- Light leaking from the edges and corners of an LCD panel
- Clouding — irregular brighter areas across a dark screen
- Whether the effect moves with your viewing angle (panel glow) or stays fixed (bleed)
Related tests
Screen Uniformity Test
Gray levels that expose bands, clouding and dirty screen effect.
5% OLED Gray Test
5% grey banding check, near-black steps and a 3×3 uniformity map.
IPS Glow Test
A guided angle check that separates panel glow from real bleed.
Black Level Test
A step wedge that finds where your display starts crushing black.
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