Ring Size Measured Size
USA inches mm
4 1 13/16 46.5
4 1/2 1 7/8 47.8
5 1 15/16 49.2
5 1/2 2 50.8
6 2 1/16 52.4
6 1/2 2 1/8 54
7 2 3/16 55.6
7 1/2 2 1/4 57.2
8 2 5/16 58.7
8 1/2 2 3/8 60.3
9 2 7/16 61.9
9 1/2 2 1/2 63.5
10 2 9/16 65.1
10 1/2 2 5/8 66.7
11 2 11/16 68.3
11 1/2 2 3/4 69.9
12 2 13/16 71.4
12 1/2 2 7/8 73
13 2 15/16 74.6