What's the average size of a human foot, and how is that figured?

Men’s size 14 is roughly one foot. That’s a little larger than most male feet.

It will vary from country /region/ethnicity may be based on average body size..I’m not sure though.

It is embarrassing sometimes that my feet are quite a bit
larger than my husbands….but I am tall 5’10 and wear 11 shoes
and he is 6 foot and wears a 9.

Edited to add:
Apparently they are not counting women’s foot size, and most men’s either. Most men are not 6 foot 2 inches, with size 11 shoe size.
A male, over the age of 13 and at a height of 6 feet 2 inches, has an average shoe size of 11 to 12. A male, over the age of 13 and at a height of 5 feet 5 inches or shorter, has an average shoe size of 7 to 9.

When I was 12, I wore a size 10½. My seventh grade classmates thought I had the largest feet they had ever seen. It was a standard oxford, and it measured (more or less) 12 inches from heel to toe.