Ronnie Cohen looks at the tenuous link between the imperial foot and human feet.
Imperial defenders often claim that imperial units are more “natural” and human in scale than metric units. It is true that human body parts have been the basis of many early forms of measurement (e.g. distance of elbow to finger tip for the cubit, width of most people’s hands for the hand – a unit used for measuring the height of horses, top thumb knuckle to thumb tip for the inch, etc). A classic example of one of these units is the foot. This applies, not only to the imperial foot, but to the other foot units historically used in different cities and countries.
In order for any measurement unit to be useful, it needs to be a standard size. So whose foot size would be the basis for the unit of the same name? That is anyone’s guess. Go to any shoe shop and you will find many different shoe sizes. Even they must be measured somehow to fit customers’ feet.
I recently came across a website for Shoe Size Converter Charts (website: https://www.shoesizingcharts.com/). It contains conversion tables for American, European and British shoe sizes with equivalents shown in inches and centimetres for men, women, youth and infants. For the same shoe numbers, men’s sizes are slightly larger than women’s.
On the Shoe Sizing Charts website, let’s look at the UK sizes for men. It lists a total of 17 sizes, increasing by 0.5 from size 5.5 to size 11.5 and by 1 from size 11.5 to size 15.5. At the lower end of the scale for UK men’s shoe sizes, size 5.5 = 23.5 cm, size 6 = 24.1 cm and size 6.5 = 24.4 cm. At the top end of the scale for UK men’s shoe sizes, size 12.5 = 29.4 cm, size 13.5 = 30.2 cm, size 14.5 = 31 cm and size 15.5 = 31.8 cm. National shoe shops (e.g. Clarks, Asos) give slightly different conversions for shoe sizes.
The closest size to the imperial foot in the Shoe Sizing Charts is the UK men’s size 13.5. So you will need at least a men’s size 13 to get an equivalent shoe size to the imperial foot (30.48 cm), an unusually large foot size. For women’s shoe sizes, the imperial foot is off the scale on the same website. The top UK women’s shoe size there is a size 10, equivalent to 27.6 cm.
The size of the imperial foot is not a typical foot size for most people. For the unit called the foot, you will find a wide range of measures for the foot on Wikipedia, most of which are now obsolete.