How type is measured
The way type is measured dates back to the days of hot metal. In 1737, the Frenchman Pierre Fournier le Jeune invented the point system of measurement, by dividing the French inch into 12 ‘lines’ which were further subdivided into six points. Some half-century later, around 1785, another Parisian, François-Ambroise Didot, settled on a standard – the didot point – which is used in continental Europe to this day.
In the United States, the point was standardized by the American Type Founders’ Association in 1886 to be 0·013837in (or 0·3515mm). Recently, the point has been further rationalized to make it exactly 1⁄72 in (0·01389in or 0·3528mm).
A pica is 12 points, and so measures 1/6 in (4.2mm). (The didot equivalent to the ...