Useful Guides

Ring sizing

UK European American

UK Size Inside  Diameter
Inches mm
G 0.5680 14.427
G1/2 0.5758 14.625
H 0.5835 14.821
H1/2 0.5913 15.019
I 0.5990 15.215
I1/2 0.6068 15.413
J 0.6145 15.608
J1/2 0.6223 15.806
K 0.6300 16.002
K1/2 0.6378 16.200
L 0.6455 16.396
L1/2 0.6533 16.594
M 0.6610 16.789
M1/2 0.6688 16.988
N 0.6765 17.183
N1/2 0.6843 17.381
O 0.6920 17.577
O1/2 0.6998 17.775
P 0.7075 17.971
P1/2 0.7153 18.169
Q 0.7230 18.364
Q1/2 0.7308 18.562
R 0.7385 18.758
R1/2 0.7463 18.956
S 0.7540 19.152
S1/2 0.7618 19.350
T 0.7695 19.545
T1/2 0.7772 19.741
U 0.7850 19.939
U1/2 0.7928 20.137
V 0.8005 20.333
V1/2 0.8083 20.531
W 0.8160 20.726
W1/2 0.8238 20.925
X 0.8315 21.120
X1/2 0.8393 21.318
Y 0.8470 21.514
Y1/2 0.8548 21.712
Z 0.8625 21.908
Z1/2 0.8703 22.106
European
Size (Approx.)
Inside  Diameter
Inches mm
46 0.5765 14.642
47 0.5890 14.961
48 0.6015 15.279
49 0.6141 15.597
50 0.6266 15.916
51 0.6391 16.234
52 0.6517 16.552
53 0.6642 16.871
54 0.6767 17.189
55 0.6893 17.507
56 0.7018 17.826
57 0.7143 18.144
58 0.7269 18.462
59 0.7394 18.780
60 0.7519 19.098
61 0.7644 19.416
62 0.7770 19.736
63 0.7895 20.054
64 0.8020 20.372
65 0.8146 20.690
66 0.8271 21.008
67 0.8396 21.326
68 0.8522 21.645
69 0.8647 21.963
American Size
(Approx.)
Inside  Diameter
Inches mm
4 0.5820 14.783
41/2 0.5980 15.189
5 0.6141 15.597
51/2 0.6300 16.002
6 0.6455 16.396
61/2 0.6620 16.815
7 0.6780 17.221
71/2 0.6940 17.628
8 0.7100 18.034
81/2 0.7265 18.453
9 0.7430 18.872
91/2 0.7590 19.279
10 0.7780 19.761
101/2 0.7940 20.168
11 0.8110 20.599
111/2 0.8271 21.008
12 0.8430 21.412
121/2 0.8590 21.819
13 0.8750 22.225