4K resolution refers to a horizontal display resolution of approximately 4,000 pixels. Specifically, it means that an image or video has about 4,000 horizontal pixels, which is approximately four times the resolution of Full HD. The dominant 4K standard in television and consumer media is 3840 × 2160 (4K UHD), while the movie projection industry uses 4096 × 2160 (DCI 4K) . The resolution of 3840 × 2160 is the minimum resolution for CEAs definition of Ultra HD displays and projectors. The resolution of 4096 × 2160 is the native resolution of all DCI-compliant 4K digital projectors and monitors.
In summary, the resolution of 4K is approximately 4,000 pixels horizontally, specifically 3840 × 2160 (4K UHD) or 4096 × 2160 (DCI 4K).
