Though humans have worn shoes for centuries, standard shoe sizes were not established until the 1300s. Today's shoe manufacturers derive their shoe sizes using those original methods, though the process has been tweaked over time to accommodate retail trends and man's ever-growing shoe size. Here is a look at how shoe sizes are calculated, as well as the difference between genders, children and countries.
The barleycorn, which had been used as a measuring standard for centuries, was first established in Britain as a means to measure shoe size in the 14th century. With each barleycorn measuring a 1/3 inch, King Edward II's foot was 36 barleycorns long, 12 inches, and thus a size 12. From that standard, sizes increased or decreased in one-barleycorn increments. For example, a size 11 was 35 barleycorns long, or 11 2/3 inches. Over the years, different regions have adopted different standards for men's, women's and children sizes.
The lowest British shoe size is a child's 0 and increases incrementally from there. Full-sizes increase by 1/3 inch, and half-sizes increase by 1/6 inch. Children's shoe sizes continue up to size 13.5 before becoming an adult size one. A child's shoe size can be estimated by multiplying the length of the foot by three, then subtracting 12 from the result. An adult size can be estimated by multiplying the length of the foot by three, then subtracting 25. There is no difference between men's and women's shoe sizes. As far as uncommon widths, narrow sizes are marked with an E and wide sizes are marked with a G or an H, though these markings are not necessarily standardised and may vary among manufacturers.
The United States' standard, usually shared by Canada, is slightly more complex. In the U.S., adult sizes begin at one, then continue in the same manner as the British system. Men's shoe sizes are therefore labelled one higher than a UK shoe of equal length. Women's sizes, however, are labelled 1.5 higher than U.S. men's sizes. Child sizes begin at 5, run to size 13.5, then start over at size 1, for adults. As a result, an adult's size 4 is much larger than a child's size 5. Despite this they increase in the standard 1/3-inch increments. There is no difference between boys' and girls' sizes. Narrow shoes are marked with an A, B, or C, and wide shoes are marked with an E.
In Australia, shoe sizes follow the same barleycorn system but with slight differences. Men's sizes in Australia and New Zealand are generally the same as the men's sizes in the UK. Women's sizes are a size larger than women's sizes in the UK. Child sizes are equivalent to child sizes in the UK.
Shoe sizes in continental Europe are measured using Paris points, which are increments of 2/3 centimetre. A shoe size in Europe is the number of Paris points in two centimetres, plus the size of the foot. A foot 26 centimetres long would be a size 42. Both adult men and women, as well as children, follow this system.
In Japan, men's shoe sizes are generally labelled 18 sizes larger than North American shoe sizes for men. Women's shoes in Japan are labelled 16 sizes larger than women's shoes in North America. Shoes in Korea are measured in millimetres and usually increase in 5mm increments. Chinese shoe sizes are based on centimetres, but there is conflicting information regarding comparable UK and U.S. sizes.
Due to differing measuring standards among shoe manufacturers, shoe material, and shoe shapes, as well as differing industrial standards in different countries, shoe sizes will vary among brands and regions. Shoe charts should be regarded as helpful guides, rather than unwavering fact. The only sure way to determine if a particular size fits is to try it on.