The length of barleycorns!! (A barleycorn is one grain of barley. It looks like a pale tan coffee bean.) Apparently our present shoe sizing methods began in the year 1324 when an appeal was made to King Edward II of England by the peasants, tradesmen, and scholars to establish some standards of measurement. The king agreed, and with the guidance of his subjects, decreed that three barleycorns (from the middle of the ear, full and round) laid end to end would henceforth be equal to one inch, and that twelve inches (36 corns) would be equal to one foot. The difference between one shoe size and the next, according to the King, was the length of one barleycorn. This formula is still the basis of the modern English, North American, and Australian shoe size methods. ---http://www.mail-archive.com/usma@colostate.edu/msg07124.html

Most of the measurement scales in use are arbitrary and evolved independently in different countries. The following are some common shoe measurements scales: - UK and Commonwealth countries. - Europe. - US (now becoming more common in Canada than UK sizing because of centralization of manufacturing in the US). - Japan. - Centimetre. - Inch. - Mondopoint (millimetres). Many other countries have their own scales, as well. In addition, the UK and US sizings are different for men and women. A men's UK 11 is approximately the same size as: - US men's 11.5 to 12. - European 45. - Japanese men's 30.5. - Inch 11-1/8. - Centimetre 28.3. - Mondopoint 283. These numbers vary to a certain extent, as manufacturers do not all produce the same size of shoes for a given foot measurement. My experience has been that a UK men's is about one size smaller numerically than the equivalent US size (e.g., UK 11 = US 12). The Bata shoe company provides a chart on their website (http://www.bata.com/tips/shoe_size_chart.php) that lists some common men's and women's shoe sizes. The UK and the US measurements for clothing are also different; I have found that there is about a one size difference between the UK and the US (e.g., US large = UK medium). Clothes that are manufactured in India usually follow UK sizing, while clothes from China somewhat follow US sizes, although they seem to be cut to a different body shape (shorter and wider).