Ultra-high-definition (UHD) television, also abbreviated UHDTV, is a digital television display format in which the horizontal screen resolution is on the order of 4000 pixels (4K UHD) or 8000 pixels (8K UHD).
Technically, a 4K UHD display has 3840 pixels horizontally and 2160 pixels vertically for a total of 8,294,400 pixels or 8.3 megapixels. An 8K UHD display has 7680 pixels horizontally and 4320 pixels vertically for a total of 33,177,600 pixels or 33.2 megapixels. Therefore, 4K UHDTV has roughly four times as many pixels as conventional HDTV (high-definition television), and 8K UHDTV has roughly 16 times as many pixels as conventional HDTV.
According to the Consumer Electronics Association, a display must have at least one digital input with a native (design) resolution of 3840 by 2160 pixels, along with an aspect ratio of at least 16:9, in order to qualify as UHD. Both the 4K and 8K UHD specifications described above scale precisely from the most common HDTV formats, avoiding image blurring and consequent loss of detail that can occur when differing screen resolutions fail to evenly divide horizontally or vertically.