Inside
diameter
Inside
circumf...
UK &
Australian
 US &
Canada
French &
Russian
German Japanese Swiss
15.04mm 47.25mm I 4 1/4 47 3/4 - - 7 3/4
15.40mm 48.38mm J 4 5/8 49 15 1/2 - 9
15.80mm 49.64mm K 5 1/8 50 - - 10
16.10mm 50.58mm L 5 1/2 51 3/4 16 - 11 3/4
16.51mm 51.87mm M 6 52 3/4 16 1/2 12 12 3/4
16.92mm 53.16mm N 6 1/2 54 17 13 14
17.35mm 54.51mm O 7 55 1/4 17 1/4 14 15 1/4
17.75mm 55.76mm P 7 1/2 56 1/2 17 3/4 15 16 1/2
18.19mm 57.15mm Q 8 57 3/4 18 16 17 3/4