The sizing difference between men’s and women’s shoes is about 1.5 sizes and two-widths . For example, a men’s shoe in size 10 would equal a women’s 11.5, while a women’s shoe in size 8 would equal a men’s size 6.5.

Furthermore, with New Balance shoes for example, there is a difference between what is considered a women’s medium width and a men’s medium width. The men’s medium or regular width is the “D width”, a women’s medium or regular width is the “B width”.

So a men’s size “10 D” (D=medium for men) would be equal to a women’s “11.5 B” or “11.5 Med” (because B=regular for women).

Note: kids shoes are usually sized on the men’s length-width scales regardless of whether it is a boys’ or girls’ style.

Shoe widths are designated by a letter-code-scale:
AAAAAA or 6A
AAAAA or 5A
AAAA or 4A
AAA or 3A
AA or 2A
A
B
C
D
E
EE or 2E
EEE or 3E
EEEE or 4E
EEEEE or 5E
EEEEEE or 6E

New Balance makes every other width:

for men:
2A: extra narrow
B: narrow
D: medium
2E: wide
4E: extra wide
6E: extra extra wide

for women:
4A: extra narrow
2A: narrow
B: medium
D: wide
2E: extra wide
4E: extra extra wide

for kids:
N: narrow
M: medium
W: wide
XW: extra wide