Eli5: Why do shoes have half sizes, rather than double the amount of whole sizes?

Question

Especially cause shoe sizes aren’t really universal anyway, making the half sizes even less meaningful. Why?

In: 193

Answer 1

Brannock device developed in 1925

https://en.wikipedia.org/wiki/Brannock_Device#:~:text=Brannock%20for%20measuring%20a%20person’s,an%20improved%20version%20in%201927.

European sizes came later, but based on the metric system.