What is a common resolution format for 4K video?

The resolution format for 4K video is primarily recognized as 3840x2160 pixels. This specification corresponds to a pixel count that is four times that of 1080p resolution (1920x1080 pixels), thereby framing it effectively as "Ultra High Definition" (UHD).

While there is another resolution for 4K known as DCI 4K (4096x2160 pixels), this is less commonly used in consumer video applications and instead is typically employed in film production. The 3840x2160 resolution is what you find in most consumer products, including televisions and streaming services, which is why it is the recognized standard for 4K video content.

Given this context, the choice of 3840x2160 pixels correctly identifies the resolution format associated with 4K video in typical usage scenarios.