Golden ratio

The golden ratio, written as phi and equal to roughly 1.618, is used in facial aesthetics as a target for several proportions at once: face length to width, mouth width to nose width, and the relationship between the thirds of the face. The idea that beautiful faces follow it comes from Renaissance drawing convention and, more recently, from Marquardt's phi mask of the 1990s — not from a finding. Attempts to reproduce a preference for phi proportions in measured populations have given mixed results at best, and the mask itself has been criticised for encoding one ethnic norm as a universal standard. Real faces spread widely on every one of these checks. A high golden-ratio score therefore means a face sits close to a particular drawing convention, which is interesting and is not the same thing as a fact about the face.