Table of Comparative Ring-Size Equivalents

Canada Standard including United States Average Diameter in Inches British Equivalent French Equivalent German Equivalent Japanese Equivalent Swiss Equivalent
000 0.39
00 0.422
0 0.454
1/2 A
3/4 A – 1/2
1 0.487 B 1
1 1/4 B – 1/2
1 1/2 0.503 C
1 3/4 C – 1/2
2 0.52 D 41 1/2 13 1/4 2 1 1/2
2 1/4 D – 1/2
2 1/2 0.536 E 42 3/4 13 3/4 3 2 3/4
2 3/4 E – 1/2
3 0.553 F 44 14 4 4
3 1/8 F – 1/2
3 3/8 G 45 1/4 5 5 1/4
3 1/2 0.569 14 1/2
3 5/8 G – 1/2 6
3 3/4 H 46 1/2 6 1/2
4 0.585 H – 1/2 15 7
4 1/4 I 47 3/4 7 3/4
4 1/2 0.601 I – 1/2 15 1/4 8
4 7/8 J 49 9
5 0.618 J – 1/2 15 3/4 9
5 1/8 K 50 10
5 3/8 K – 1/2 10
5 1/2 0.634 L 51 3/4 16 11 3/4
5 7/8 L – 1/2 11
6 0.65 M 52 3/4 16 1/2 12 12 3/4
6 1/4 M – 1/2
6 1/2 0.666 N 54 17 13 14
6 3/4 N – 1/2
7 0.683 O 55 1/4 17 1/4 14 15 1/4
7 1/4 O – 1/2
7 1/2 0.699 P 56 1/2 17 3/4 15 16 1/2
7 3/4 P – 1/2
8 0.716 Q 57 3/4 18 16 17 3/4
8 1/4 Q -1/2
8 1/2 0.732 18 1/2 17
8 5/8 R 59 19
8 7/8 R – 1/2
9 0.748 19 18
9 1/8 S 60 1/4 20 1/4
9 3/8 S – 1/2
9 1/2 0.764 19 1/2 19
9 5/8 T 61 1/2 21 1/2
10 0.781 T – 1/2 20 20
10 1/4 U 62 3/4 21 22 3/4
10 1/2 0.797 U – 1/2 20 1/4 22
10 5/8 V 63 3/4 23 3/4
11 0.814 V – 1/2 20 3/4 23
11 1/8 W 65 25
11 3/8 W – 1/2
11 1/2 0.83 21 24
11 5/8 X 66 1/4 26 1/4
11 7/8 X – 1/2
12 0.846 Y 67 1/2 21 1/4 25 27 1/2
12 1/4 Y – 1/2
12 1/2 0.862 Z 68 3/4 21 3/4 26 28 3/4
12 3/4 Z – 1/2
13 0.879 22 27
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