Face shape test

A face shape test classifies a face into one of six conventional categories — oval, round, square, heart, oblong or diamond — using measurements rather than judgement. The inputs are three width ratios and one angle: face length divided by cheekbone width, jaw width divided by cheekbone width, forehead width divided by cheekbone width, and the angle at the corner of the jaw. Different tools set the boundaries between categories differently, which is why two of them can disagree about the same face and both be internally consistent; there is no natural gap in any of these ratios where one shape stops and the next begins. The categories exist to make a practical decision easier — which haircut, which glasses, which beard line — and they are a convention for doing that, not a measurement of anything biological.