International Ring Sizing

Diameter - Internal diameter in millimeteres.

Circumference - Internal circumference in millimeteres
Britain Europe Japan USA Diameter Circumference
      0 11.54 36.25
A       11.90 37.38
    0   12.00 37.70
A1/2       12.10 38.01
B       12.30 38.64
      1 12.37 38.86
B1/2       12.50 39.27
      11/4 12.58 39.52
C       12.70 39.90
  0.15   11/2 12.78 40.15
C1/2 0.53     12.90 40.53
  0.84 1 13/4 13.00 40.84
  1.00     13.05 41.00
D 1.15     13.10 41.15
  1.50   2 13.21 41.50
D1/2 1.78     13.30 41.78
  1.88 2   13.33 41.88
  2.00     13.37 42.00
  2.13   21/4 13.41 42.13
E 2.41     13.50 42.41
  2.76   21/2 13.61 42.76
  2.91 3   13.66 42.91
E1/2 3.00     13.69 43.00
  3.42   23/4 13.82 43.42
F 3.67     13.90 43.67
  3.98 4   14.00 43.98
  4.00     14.01 44.00
  4.14   3 14.05 44.14
Britain Europe Japan USA Diameter Circumference
F1/2 4.30     14.10 44.30
  4.74   31/4 14.24 44.74
G 4.92     14.30 44.92
  5.00     14.32 45.00
  5.02 5   14.33 45.02
  5.40   31/2 14.45 45.40
G1/2 5.55     14.50 45.55
  6.00     14.64 46.00
  6.02   33/4 14.65 46.02
  6.06 6   14.66 46.06
H 6.18     14.70 46.18
  6.68   4 14.86 46.68
H1/2 6.81     14.90 46.81
  7.00     14.96 47.00
  7.12 7   15.00 47.12
  7.34   41/4 15.07 47.34
I 7.44     15.10 47.44
  7.97   41/2 15.27 47.97
  8.00     15.28 48.00
I1/2 8.07     15.30 48.07
  8.16 8   15.33 48.16
  8.63   43/4 15.48 48.63
J 8.69     15.50 48.69
  9.00     15.60 49.00
  9.20 9   15.66 49.20
Britain Europe Japan USA Diameter Circumference
J1/2 9.32   5 15.70 49.32
K 9.95   51/4 15.90 49.95
  10.00     15.92 50.00
  10.27 10   16.00 50.27
K1/2 10.58   51/2 16.10 50.58
  11.00     16.23 51.00
L 11.24   53/4 16.31 51.24
  11.30 11   16.33 51.30
L1/2 11.87   6 16.51 51.87
  12.00     16.55 52.00
  12.34 12   16.66 52.34
M 12.46     16.70 52.46
  12.56   61/4 16.73 52.56
  13.00     16.87 53.00
M1/2 13.09     16.90 53.09
  13.16   61/2 16.92 53.16
  13.41 13   17.00 53.41
N 13.72     17.10 53.72
  13.85   63/4 17.14 53.85
  14.00     17.19 54.00
N1/2 14.35     17.30 54.35
  14.44 14   17.33 54.44
  14.51   7 17.35 54.51
O 14.98     17.50 54.98
  15.00   71/4 17.56 55.00
  15.48 15   17.66 55.48
Britain Europe Japan USA Diameter Circumference
O1/2 15.61     17.70 55.61
  15.76   71/2 17.75 55.76
  16.00     17.83 56.00
P 16.23     17.90 56.23
  16.45   73/4 17.97 56.45
  16.55 16   18.00 56.55
P1/2 16.86     18.10 56.86
  17.00     18.14 57.00
  17.15   8 18.19 57.15
Q 17.49     18.30 57.49
  17.59 17   18.33 57.59
  17.77   81/4 18.39 57.77
  18.00     18.46 58.00
Q1/2 18.12     18.50 58.12
  18.40   81/2 18.59 58.40
  18.62 18   18.66 58.62
R 18.75     18.70 58.75
  19.00   83/4 18.78 59.00
R1/2 19.38     18.90 59.38
  19.66   9 18.99 59.66
  19.69 19   19.00 59.69
S 20.00     19.10 60.00
  20.38   91/4 19.22 60.38
S1/2 20.63     19.30 60.63
  20.73 20   19.33 60.73
  20.98   91/2 19.41 60.98
  21.00     19.42 61.00
Britain Europe Japan USA Diameter Circumference
T 21.26     19.50 61.26
  21.67   93/4 19.63 61.67
  21.76 21   19.66 61.76
T1/2 21.89     19.70 61.89
  22.00     19.74 62.00
  22.33   10 19.84 62.33
U 22.52     19.90 62.52
  22.83 22   20.00 62.83
  23.00   101/4 20.05 63.00
U1/2 23.15     20.10 63.15
  23.59   101/2 20.24 63.59
V 23.77     20.30 63.77
  23.87 23   20.33 63.87
  23.99     20.37 63.99
  24.28   103/4 20.46 64.28
V1/2 24.40     20.50 64.40
  24.91 24   20.66 64.91
  24.97   11 20.68 64.97
W 25.00     20.69 65.00
  25.60   111/4 20.88 65.60
W1/2 25.66     20.90 65.66
  25.97 25   21.00 65.97
  26.00     21.01 66.00
  26.22   111/2 21.08 66.22
X 26.29     21.10 66.29
X1/2 26.92   103/4 21.30 66.92
  27.01     21.33 67.01
Y 27.51   12 21.49 67.51
  28.02     21.65 68.02
  28.05 27   21.66 68.05
Y1/2 28.20   121/4 21.71 68.20
Z 28.77   121/2 21.89 68.77
  28.99     21.96 68.99
  29.12 28   22.00 69.12
Britain Europe Japan USA Diameter Circumference
Z1/2 29.43     22.10 69.43
  29.49   123/4 22.12 69.49
Z+1 29.99     22.28 69.99
  30.15 29 13 22.33 70.15
Z+11/2 30.69     22.50 70.69
  30.81   131/4 22.54 70.81
  31.00     22.60 71.00
  31.19 30   22.66 71.19
Z+2 31.31     22.70 71.31
  31.47   131/2 22.75 71.47
Z+21/2 32.01   133/4 22.92 72.01
  32.26 31   23.00 72.26
Z+3 32.57     23.10 72.57
  32.76   14 23.16 72.76
  33.01     23.24 73.01
Z+31/2 33.20     23.30 73.20
  33.32     23.34 73.32
  33.29 32   23.33 73.29
  33.42   141/4 23.37 73.42
Z+4 33.83     23.50 73.83
  33.98   141/2 23.55 73.98
  34.33 33   23.66 74.33
Z+41/2 34.46     23.70 74.46
  34.71   143/4 23.78 74.71
 > 34.99     23.87 74.99
Z+5 35.08     23.90 75.08
  35.40 34 15 24.00 75.40
Z+51/2 35.71     24.10 75.71
  36.00   151/4 24.19 76.00
Z+6 36.34     24.30 76.34
  36.43 35   24.33 76.43
  36.69   151/2 24.41 76.69
Z+61/2 37.00     24.51 77.00
  37.31   153/4 24.61 77.31
  37.47 36   24.66 77.47
Z+7 37.60     24.70 77.60
  38.00   16 24.83 78.00
Z+71/1 38.23     24.90 78.23
  38.54 37 161/4 25.00 78.54