Why are shoe sizes not standardized?
Because the exact shape of a last differs from shoe to shoe, sizes will inevitably vary a bit too. Adding to that, men's, women's and kid's lasts are all different, so the discrepancies in sizes is even more pronounced across those types of shoes.
How are shoe sizes determined?
While different manufacturers still sometimes vary their sizing slightly from one another, today in America, the sizing generally adheres relatively closely to a formula of 3 times the length of the foot in inches (the barleycorn length), less a constant (22 for men and 21 for women).
Does shoe width change with size?
Shoe size and shoe width tend to be proportional in standard sizing, so large shoes may run a little wider than necessary if you have long, but narrow feet. However, we'd advise against opting for a larger shoe size, solely for the purpose of getting a wider fit, as this could cause a trip hazard.