The term 4K is used to describe several resolutions with a width of about 4,000 pixels. 4,096 x 2,160 was established as the native 4k resolution by the Digital Cinema Initiatives. Most of the different resolutions are used in digital cinematography while the resolution 3,840 x 2,160, which is known as 4K UHDTV (2160p), is commonly used in digital television.

4K has become a term to market ultra high definition television (UHDTV) products. Technically 4K and UHDTV are not the same. The 4K industry standard is the resolution of 4,096 x 2,160 pixels at a 1.9:1 aspect ratio, while UHDTV has a resolution of 3,840 x 2,160 at a aspect ratio of 1.78:1 (16:9).

The different widths and heights of the 4K resolutions result in varying aspect ratios and pixels:

Format	Resolution	Aspect ratio	Pixels
Digital Cinema Initiatives native 4K resolution	4,096 x 2,160	1.9:1 (256:135)	8,847,360
Digital Cinema Initiatives widescreen standard (Flat cropped)	3,996 x 2,160	1.85:1	8,631,360
Digital Cinema Initiatives anamorphic widescreen (CinemaScope cropped)	4,096 x 1,716	2.39:1	7,028,736
UHDTV	3,840 x 2,160	1.78:1 (16:9)	8,294,400

In the following image

• native resolution is presented by the image itself,
• flat resolution is presented by the red rectangle,
• scope resolution is presented by the green rectangle and
• UHDTV resolution is presented by the blue rectangle.

The largest ultra high definition television standard is the 8K resolution.