International Conversion Chart

Ring Diameter (MM) USA/Canada United Kingdom France Germany Japan Switzerland
14.0 mm. 3 F 44 14 4 4
14.4 mm. G 45¼ 14½ 6⅓
14.8 mm. 4 46½ 15 7
15.2 mm. 47¾ 15¼ 8 8
15.6 mm. 5 49 15¾ 9
16.0 mm. L 50¾ 16 10½ 10¾
16.5 mm. 6 M 51½ 16½ 12 12¾
16.9 mm. N 52¾ 17 13 14
17.3 mm. 7 O 54 17¼ 14 15¼
17.7 mm. P 55¼ 17¾ 15 16½
18.2 mm. 8 Q 56¾ 18 16 17¾
18.6 mm. 58 18½ 17 18½
19.0 mm. 9 59¼ 19 18 20
19.4 mm. 60¾ 19½ 19 21
19.8 mm. 10 61¾ 20 20 21¾
20.2 mm. 10½ 62¾ 20¼ 22 22¾
20.6 mm. 11 64¼ 20¾ 23 24
21.0 mm. 11½ 66 21 24 25¾
21.4 mm. 12 Y 67¼ 21¼ 25 27½
21.8 mm. 12½ Z 68 21¾ 26 28¾
22.2 mm. 13 - 69 22 27 29¼
22.6 mm. 13½ - - - - -