The most common sizes for women are 6 and 7, and for men 10 and 11

US	British	European
3	F	44
	F 1/2	45
3 1/2	G
4	H	46
4 1/2	H 1/2	47
	I	48
5	J	49
	J 1/2	50
5 1/2	K
	K 1/2	51
6	L
		52
	L 1/2
6 1/2	M
		53
	M 1/2
7	N	54
	N 1/2
		55
7 1/2	O
	O 1/2
		56
8	P
		57
	P 1/2
	Q
8 1/2		58
	Q 1/2
	R	59
9
	R 1/2
		60
	S
9 1/2
	S 1/2
		61
	T
10	T 1/2	62
	U
		63
10 1/2	U 1/2
	V	64
	V 1/2
11
	W	65
	W 1/2
11 1/2		66
	X
	X 1/2
		67
12
	Y
		68
	Y 1/2
12 1/2
	Z
	Z 1/2
13
		70