4K resolution
The term "2160p" could be applied to any format with a height of 2160 pixels, but it is most commonly used in reference to the 4K UHDTV resolution of 38402160 due to its association with the well-known 720p and 1080p HDTV formats. Although 38402160 is both a 4K resolution and a 2160p resolution, these terms cannot always be used interchangeably since not all 4K resolutions are 2160 pixels tall, and not all 2160p resolutions are ≈4000 pixels wide. However, some companies have begun using the term "4K" to describe devices with support for a 2160p resolution, even if it is not close to 4000 pixels wide. For example, many "4K" dash cams only support a resolution of 28802160 (4∶3); although this is a 2160p resolution, it is not a 4K resolution. Samsung also released a 51202160 (64∶27) TV, but marketed it as a "4K" TV despite its 5K-class resolution.
Graphics display resolution
This resolution, sometimes referred to as 4K UHD or 4K2K, has a 16:9 aspect ratio and 8,294,400 pixels. It is double the size of Full HD (19201080) in both dimensions for a total of four times as many pixels, and triple the size of HD (1280720) in both dimensions for a total of nine times as many pixels. 38402160 was chosen as the resolution of the UHDTV1 format defined in SMPTE ST 2036-1, as well as the 4K UHDTV system defined in ITU-R BT.2020 and the UHD-1 broadcast standard from DVB. It is also the minimum resolution requirement for CEA's definition of an "Ultra HD" display. Prior to the publication of these standards, it was sometimes casually referred to as "QFHD" (Quad Full HD).