Backlight Bleed vs. IPS Glow

Put an LCD monitor on a full black screen in a dark room and it'll almost never look perfectly black, even straight out of the box. That scares a lot of people into returning a perfectly healthy screen, because two different effects are at work, and only one of them is a fault.

What backlight bleed is

An LCD screen doesn't make its own light. A backlight shines constantly from behind, and the liquid crystal layer blocks it to make black. Where the screen is held slightly unevenly in its frame, light escapes around the edges, usually as bright streaks or blotches along the sides, or a pool of light in one corner. That's backlight bleed. It's a physical flaw in how the screen was put together, it stays in the same place wherever you sit, and bad cases are a fair reason to return a display.

What IPS glow is

IPS glow is part of how the screen technology works, not a fault. On IPS screens, the liquid crystals can't block light perfectly when you look at them from an angle, so dark areas take on a pale, silvery sheen that's strongest in the corners nearest your eyes. Every IPS screen does this to some degree, including expensive ones. VA screens show much less of it but have worse viewing angles; OLED shows none at all, because pixels that are off give out no light.

How to tell them apart

Move your head. IPS glow shifts, fades or moves to a different corner as your viewing angle changes, and it mostly disappears when you look at the screen straight on from a bit further away. Backlight bleed stays put: the same streak is in the same place from every angle, because it's light physically escaping at the edge. Check in a dark room with the brightness at your normal setting, and step back a little. At arm's length most glow disappears, while bleed stays. Use the Backlight Bleed Check for a true full-screen black to judge against.

How much is normal

Some unevenness on any LCD is expected, and a pitch-black room at full brightness makes it look far worse than anything you'd notice in real use. The practical test is whether you can see it while actually using the screen. If the black bars on films, dark game scenes or a dark-mode app show visible patches at normal brightness, it's worth doing something about. If it only shows up on a black test screen with the lights off, most screens look like that. Manufacturers rarely give a limit for bleed the way they do for faulty pixels, so it's usually handled under their general return policy rather than the pixel rules in the manufacturer policy comparison — which makes the return window the deadline that matters.

Bleed and glow both affect whole areas. A single bright dot on a black screen is something else entirely: run the full test and compare with dead, stuck and hot pixels.