This myth is commonly stated in the British media and presumably only refers to the foot. What part of the body is a pound? What naturally corresponds to a pint?

However, a little thought shows that this is an empty justification for using imperial. A unit needs to have a standard size otherwise there would be complete chaos. Human feet are not a standard size and so there is no natural size for the unit. The fact that human feet vary led to many different standard feet in Europe in the past.

In fact very few people have feet that are as large as the imperial foot. You would need a British size 12 ½ foot! The vast majority of people have smaller feet. The average human foot is 24 cm versus 30.48 cm for the imperial foot.

If an imperial foot is “natural” then by implication most people have unnaturally small feet! If in doubt try measuring your own feet.

A much stronger argument is that decimal numbers are “natural” since all able bodied people have ten digits.