Backlight Bleed Test
Show a full black screen to check an LCD monitor or TV for backlight bleed, IPS glow and clouding. Free, instant, nothing to install.
How to test
- 01Dim the room and set brightness to what you normally use, not maximum.
- 02Press Start to fill the screen with black, then very dark gray.
- 03Look from straight on at a normal distance, then move your head left and right.
- 04Photos exaggerate bleed: judge with your eyes, not your phone camera.
What causes it
An LCD doesn't make its own light. A backlight shines through the panel, and the liquid crystal blocks it to make black. Where the frame presses on the panel, or the layers are bonded unevenly, some light leaks around the edges: that's backlight bleed.
IPS panels also show IPS glow, a silvery sheen in the corners caused by the viewing angle rather than a leak. It changes as you move your head; bleed doesn't. OLED screens have no backlight, so they can't bleed.
How much is normal
Almost every LCD shows some bleed on a full black screen in a dark room. What matters is whether you notice it in normal use: dark film scenes, games at night, a loading screen. Mild, even bleed at the edges is normal; bright patches that stand out in everyday content are reasonable grounds for a return.
Tips for a fair test
- Use your normal brightness, not maximum: bleed scales with the backlight.
- Look from your usual seat. IPS glow grows the closer you sit and the more you look from an angle.
- Don't judge from phone photos: cameras raise exposure on black and exaggerate bleed.
- Comparing two screens? Test both at the same brightness and in the same room light.
What your result means
Light patches at the edges that stay put when you move
Backlight bleed: light leaking past the panel's edges.
Mild bleed is common. Strong bleed visible in normal use is worth a return.
A glow in the corners that shifts as you move your head
IPS glow: normal for IPS panels, not a defect.
Sit further back, add some ambient light, or lower brightness.
Uneven blotches across the black
Clouding (mura).
Normal at low levels on LCDs; heavy clouding on a new screen is worth a return.
Even black everywhere
No noticeable bleed.
Your screen passes.
How to fix it
LCD monitor or TV
- Lower the brightness: bleed scales with backlight level.
- Give a new panel a few days; slight bleed sometimes settles.
- Don't loosen screws or press the bezel on a screen you might return: it can void the warranty.
Questions
Is some backlight bleed normal?
Yes. Most LCD screens leak a little light at the edges. It's a defect when it's obvious in normal use, not only on a black screen in a dark room.
How do I tell IPS glow from backlight bleed?
Move your head. IPS glow changes with your viewing angle; bleed stays in the same place.
Do OLED screens have backlight bleed?
No. OLEDs have no backlight, so black is truly black. Use the burn-in test instead.
Is anything uploaded?
No. The test runs entirely in your browser. Nothing you see, say or film is sent to us or stored anywhere.