U.S SIZES AUS/UK SIZES DIAMETER (MM) CIRCUMFERENCE (MM)
MIDI SIZES 3 14.05 44.14
4 H 1/2 14.86 46.68
5 J 1/2 15.70 49.32
STANDARD SIZES 6 M   16.51 51.87
7 O 17.35 54.51
8 Q 18.19 57.15
9 R 3/4 18.89 59.34