Traditional nearly square aspect ratio used for most current analog television screens and IMAX movie theater screens. This aspect ratio will slowly be phased out in favor of the wider, more panoramic and movie-like 16:9 ratio. Video displays using a 4-by-3 ratio display images 4 units wide (horizontal measure) by 3 units tall (vertical measure).

The 4:3 ratio performs fine for television programming, which was designed for it, but it creates problems with movie material originally designed for theater release. The movies are created with a wider, more rectangular aspect ratio (16:9 or wider) in order to create a larger viewing surface and bring the viewer more into the film. On a traditional 4-by-3 aspect ratio display, these movies must be letterboxed (where the entire image is shown with black bars above and below it) or cut down in size (pan and scan where portions of the image are cut out and not displayed resulting in an image which fills the 4:3 screen but does not contain the entire movie image as seen in the theater).