Inch Ounces Irons Millimeters 1/64 1 .75 0.4 1/32 2 1.5 .8 3/64 3 2.25 1.2 1/16 4 3.0 1.6 5/64 5 3.75 2.0 3/32 6 4.5 2.4 7/64 7 5.25 2.8 1/8 8 6.0 3.2 9/64 9 6.75 3.6 5/32 10 7.5 4.0 11/64 11 8.25 4.4 3/16 12 9.0 4.8 13/64 13 9.75 5.2 7/32 14 10.5 5.6 15/64 15 11.25 6.0 1/4 16 12.0 6.4 17/64 17 12.75 6.8 9/32 18 13.5 7.2 (306)