Cephalic index
The cephalic index or cranial index is a craniometric measure, the ratio of the maximum width (bipareital diameter or BPD, side to side) of the head of an organism (human or animal) multiplied by 100 divided by its maximum length (occipitofrontal diameter or OFD, front to back).
Humans are characterized by having either a dolichocephalic (long headed), mesaticephalic (moderate headed), or brachycephalic (short headed) cephalic index or cranial index.
The cephalic index was widely used by anthropologists to categorize human populations. See the article on Nordicism.
It is now mainly used to describe individuals' appearances and for estimating the age of fetuses for legal and obstetrical reasons. The index is also used to categorize animals, especially dogs and cats.
