This size guide is relevant whether you’re determining mens ring sizes in the UK or ladies ring sizes. Note that the sizes below include half sizes - quarter sizes and three quarter sizes are also often available.
|
Inside Diameter (mm) |
Inside Circumference (mm) |
Ring Size UK |
|
11.95 |
37.54 |
A |
|
12.18 |
38.26 |
A 1/2 |
|
12.37 |
38.86 |
B |
|
12.60 |
39.58 |
B 1/2 |
|
12.78 |
40.15 |
C |
|
13.00 |
40.84 |
C 1/2 |
|
13.21 |
41.50 |
D |
|
13.41 |
42.13 |
D 1/2 |
|
13.61 |
42.76 |
E |
|
13.83 |
43.45 |
E 1/2 |
|
14.05 |
44.14 |
F |
|
14.15 |
44.45 |
F 1/2 |
|
14.36 |
45.11 |
G |
|
14.56 |
45.74 |
G 1/2 |
|
14.65 |
46.02 |
H |
|
14.86 |
46.68 |
H 1/2 |
|
15.04 |
47.25 |
I |
|
15.27 |
47.97 |
I 1/2 |
|
15.40 |
48.38 |
J |
|
15.70 |
49.32 |
J 1/2 |
|
15.80 |
49.64 |
K |
|
16.00 |
50.27 |
K 1/2 |
|
16.10 |
50.58 |
L |
|
16.41 |
51.55 |
L 1/2 |
|
16.51 |
51.87 |
M |
|
16.71 |
52.50 |
M 1/2 |
|
16.92 |
53.16 |
N |
|
17.13 |
53.82 |
N 1/2 |
|
17.35 |
54.51 |
O |
|
17.45 |
54.82 |
O 1/2 |
|
17.75 |
55.76 |
P |
|
17.97 |
56.45 |
P 1/2 |
|
18.19 |
57.15 |
Q |
|
18.35 |
57.65 |
Q 1/2 |
|
18.61 |
58.47 |
R |
|
18.80 |
59.06 |
R 1/2 |
|
19.10 |
60.00 |
S |
|
19.31 |
60.66 |
S 1/2 |
|
19.51 |
61.29 |
T |
|
19.84 |
62.33 |
T 1/2 |
|
20.02 |
62.89 |
U |
|
20.20 |
63.46 |
U 1/2 |
|
20.32 |
63.84 |
V |
|
20.68 |
64.97 |
V 1/2 |
|
20.76 |
65.22 |
W |
|
20.94 |
65.78 |
W 1/2 |
|
21.18 |
66.54 |
X |
|
21.30 |
66.92 |
X 1/2 |
|
21.49 |
67.51 |
Y |
|
21.69 |
68.14 |
Y 1/2 |
|
21.89 |
68.77 |
Z |
|
22.10 |
69.43 |
Z 1/ |