The LG UF6400 LED TV is the second 4k TV we have seen from LG which uses the less accurate RGBW pixel structure. Like most other IPS TVs, its picture quality isn't that great due to poor contrast ratio and black uniformity. Its wide viewing angle is its strong point, but unfortunately, this TV doesn't excel at anything.
It isn't a TV that will turn heads, but it doesn't look bad, either. The stand is very sturdy, but it will require a table almost as wide as the TV.
Because of its poor blacks and contrast, movies won't be great if you watch them in a dark room. With the lights on, this won't be as big of a problem. The TV is judder-free if you watch Blu-ray discs, which is great.
This isn't the worst TV we have seen for blacks, but it is still near the bottom of the list. Blacks will look gray when you watch this TV in the dark.
There isn't much 'dirty screen effect' but the corners of the screen are very dark. This could be distracting while watching hockey, in particular.
This is always the strong point of IPS TVs. The colors of the UF6400 don't lose much saturation when viewed from the side. This TV is suitable for a wide family room.
Update 01/06/2017: We have changed the methodology of testing. Since this is an old TV which we don't have anymore, we extrapolated the results from 2016 TVs.
The black uniformity isn't that bad for an IPS TV, but most VA LED TVs will look better.
This TV doesn't display true 4k resolution. It includes a white pixel in its pixel substructure. It isn't apparent from farther away, but can be obvious from up close, like if you use the TV as a PC monitor. Text can look blurry.
Direct light produces rainbow reflections.
While it can get bright enough, the TV isn't able to overcome strong light. It also get a yellow tint when there is a lot of light in the room.
The less accurate RGBW 4k panel of the LG UF6400 adds a white pixel, which can be seen in this close-up picture of the screen.
Here again, the LG UF6400 is average. The motion blur trail isn't too long, but the uniformity of the screen is bad, which could be apparent on playing surfaces, since those are mostly solid colors.
The motion blur isn't particularly bad, and it won't be a problem for most content.
For 24p sources like Blu-ray, the TV is able to remove judder correctly. Unfortunately, movies over cable or from some streaming services will still have judder inconsistently. Since this is a 60 hz TV and it has TruMotion, it can only interpolate signals under 60 hz.
Only casual gaming would be suitable on this TV, since the input lag is average-high. Any competitive gaming should be avoided. The lag is even more apparent when using the TV as a PC monitor. Combined with the fact that 4k doesn't look that sharp up-close, this TV wouldn't be great as a PC monitor (even though it is compatible with most PC inputs).
Under game mode, the TV is responsive enough for casual gaming, but any hardcore players will feel a bit of lag on their controller inputs. Compared to other 2015 TVs, the input lag is average-high.
Most of the modes tested work on this TV except for 1080p@120Hz. To achieve 4k @ 60Hz turn on 'HDMI Ultra HD Deep Color'. To add chroma 4:4:4, enable 'HDMI-PC' under the picture menu. Unfortunately, if you use the TV as a PC monitor, the input lag (same as in game mode) will be quite apparent. Even more so for games like first person shooters, which require fast reflexes.
The sound of the LG UF6400 is like that of most other TVs. It can get loud enough without much distortion, but anyone who cares about sound would benefit from using a dedicated soundbar or speaker system.
Note: Sound Quality test for TVs reviewed before 2017 was performed at 75dB, 85dB, and Max SPL. Starting 2017, the target SPL levels have been changed to 70dB, 80dB, and Max dB SPL.
Poor frequency response, especially under heavy load, which seems to cause significant pumping and compression. The loudness and bass-extension are decent.
Decent distortion performance at all levels.
WebOS is a great smart TV platform and has a good amount of available apps. Unfortunately, you don't get the smart remote with this TV, so it isn't the best way to experience the platform. It takes more time to input text, but other than that, the navigation is straightforward. You can read our overview of LG's WebOS here.
Unfortunately, the LG UF6400 isn't a great TV. Movie lovers will find that the picture lacks some punch and gamers won't be satisfied with the responsiveness. Even if the TV is compatible with most PC inputs, the lag and somewhat-blurry 4k resolution will still make it a no-go. The only scenario where this TV could be viable is in an average-lit room with off-axis seating. For most people's needs, there is a better TV than this one.