Mediocrity and average type are today considered terms with a negative image. However, in the 19th century, they are invented as ideal images and formalized through techniques of measurement and calculation. For the first time, not only are vast amounts of data collected, but numbers are also seen as a guarantee of objectivity in general. A prerequisite for this is a concept of numbers that detaches itself from its material basis—such as fingers, toes, tally sticks, or counting stones—and becomes an abstract, universal symbol and calculation. Three case studies form the backbone of the work: Johann Gottfried Schadow's artistic ideal of 'Medium Size,' Adolphe Quételet's statistical theorem of the 'Homme moyen,' and the development of the first ready-to-wear sizes. Here, representative and common measurements are initially determined from the male body and applied to humanity as a whole. However, it becomes problematic.