Aspect Ratio

Aspect ratio is the proportional relationship between the width and height of an image or video frame, expressed as width:height or as a decimal. The dominant aspect ratios in cinema and post-production are: 1.85:1 (flat theatrical, the standard wide ratio for most feature films), 2.39:1 (anamorphic or 'CinemaScope,' the extra-wide ratio for spectacle features and many modern art films, originally created by anamorphic lens optics), 1.78:1 (16:9, the HD broadcast and streaming standard), 4:3 (1.33:1, the pre-HD broadcast standard, used artistically in some modern films), 1:1 (square, used in social media especially Instagram), 9:16 (vertical 16:9, the smartphone-vertical standard for TikTok, Instagram Reels, YouTube Shorts), and 1.43:1 (IMAX, the format used for full-frame IMAX cameras). Aspect ratio determines how shots are composed at acquisition and how they are processed in post: a film shot in 2.39:1 anamorphic typically captures at 1.43:1 on a Super 35mm sensor with the anamorphic squeeze; in post the squeeze is desqueezed to produce the 2.39:1 final aspect. Wider aspects are achieved either by anamorphic optics (preserving full sensor area for vertical resolution) or by cropping the top and bottom of a 16:9 capture (sacrificing vertical pixels). Mixed-aspect delivery (a feature in 2.39:1 letterboxed in a 1.78:1 streaming container) is the standard for modern theatrical-to-streaming pipelines. Reference: SMPTE RP 2007 and various studio delivery specifications.