LG 38UC99 review: 4K UltraWide

LG brings 21:9 UltraWide to another level


Colour quality

Our new test method gives even more insight into the colour quality. 

First we look at the coverage of the sRGB colour space of the LG 38UC99. In standard mode we see that the coverage of this is not a problem, we even measure a slightly larger colour space.

The second part that we look at is the colour temperature of white at the standard setting. At 6651K in the middle of the monitor this is excellent. On the next page you can see that this slightly increases towards the edges, but amply stays below the – in our opinion – critical boundary of 7000 K.

We were already measuring the colour- and grayscale value deviation based on the CIE2000 norm (we used the CIE1994 norm for a long time), but with the new test method we also add in the standard deviation. Simply put this gives an indication of the amount at which the sub-measurements that the average deviations are based on, deviate from the average measurement. Aside from that the averages are now based on a bigger number of sub-measurements. These can be found with the screenshots for every tested product. There you can also find the so-called saturation sweeps, that show to what extent the head- and support colours, meaning RGB and CMY, deviate from the desired values in a continuum.

The average colour deviation is a little bit higher than what we would expect from a calibrated screen with a DeltaE-value of 3.35, but it is definitely not a bad score. This monitor is not primarily meant for image processing – it does not have a wide gamut panel – but for a mix of diverse applications. For most forms of image processing this deviation is acceptable; software calibration will undoubtedly be able to improve on this. The SD of 1.88 is reasonable, but not spectacular.

The test results for the grayscale deviation and the standard deviation are reasonable, although we expect a little bit more from a monitor in this price range, especially considering the claimed factory calibration.



Taking a look at the colour checker results, we primarily see excellent values. Only red, sky blue and skin tones are a bit high, as well as the gray values, on which more later. Calibration of the video signal (in the software) should be able to fix this. In the simple colour gamut measurement we see that most points are in place, we only see a (very) small case of saturation. The saturation sweeps are not that great, especially not blue-yellow and cyan-red.

  • LG 38UC99-W
  • LG 38UC99-W
  • LG 38UC99-W


The average gamma value of 2.25 is excellent and the standard deviation is not that bad either. Note the peak at 10% brightness and that green deviates more than we would like – this also results in a light green cast in the gray values.

LG 38UC99-W

Product discussed in this review

  Product Lowest price

LG 38UC99-W

37.5 inch, 3840x1600, 111 ppi, IPS, AMD FreeSync, 75 Hz, HDMI input, DisplayPort input, 5 ms, 300 cd/m², 1000 : 1

Specifications Test results Reviews Prices


Avg. $1,299.99
4 shops, 4x stock

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