Craniometry is measurement of the cranium (the main part of the skull), usually the human cranium. It is a subset of cephalometry, measurement of the head, which in humans is a subset of anthropometry, measurement of the human body. It is distinct from phrenology, the pseudoscience that tried to link personality and character to head shape, and physiognomy, which tried the same for facial features. However, these fields have all claimed the ability to predict traits or intelligence.

It was once intensively practised in anthropology, in particular in physical anthropology in the 19th and the first part of the 20th century. Theories attempting to scientifically justify the segregation of society based on race became popular at this time, one of their prominent figures being Georges Vacher de Lapouge (1854–1936), who divided humanity into various, hierarchized, different "races", spanning from the "Aryan white race, dolichocephalic" (from the Ancient Greek kephalê, head, and dolikhos, long and thin), to the "brachycephalic" (short and broad-headed) race. On the other hand, craniometry was also used as evidence against the existence of a "Nordic race" and also by Franz Boas who used the cephalic index to show the influence of environmental factors. Charles Darwin used craniometry and the study of skeletons to demonstrate his theory of evolution first expressed in On the Origin of Species (1859).

More direct measurements involve examinations of brains from corpses, or more recently, imaging techniques such as MRI, which can be used on living persons. Such measurements are used in research on neuroscience and intelligence.

Quite separately, certain artists from the 15th century onward made measurements of heads and skulls with a view to attaining greater accuracy in their representation of those parts of the human frame. Bernard Palissy and Albrecht Dürer were pioneers in such researches.