Did you ever wonder why a foot is 12 inches in length? The most common theory is that King Henry I of England wanted to standardize length and therefore used his booted foot, being 12 inches. It is also said that the yard was based on the distance from his nose to his thumb of his extended arm, 36 inches. Thanks to this standardization, the lengths haven’t changed since the 12th century. If this weren’t the case, the foot and yard would’ve varied with the different monarch’s shoe size and arm length.