Women's

Sock Size	Calf Circumference
2	9.5 - 12 in.
3	12.5 - 15 in.
4	15.5 - 17.5 in.

Measure the calf circumference at the widest point

Men's

Sock Size	Calf Circumference
3	12.5 - 15 in.
4	15.5 - 17.5 in.
5	18 - 20 in.

Measure the calf circumference at the widest point