ISO (International Organization for Standardization): International standardization and unification of ISO 8653, a ring size standard that differs from country to country.
| ISO-8653 |
Japan and USA, UK, Hong Kong comparison |
| Japan |
Diameter(mm) |
Inner circumference(mm) |
USA |
UK |
Hong Kong |
| 41 |
1 |
13 |
40.8 |
1 |
C |
|
| 42 |
2 |
13.3 |
41.9 |
2 |
D |
|
| 43 |
3 |
13.7 |
42.9 |
2.5 |
E |
|
| 44 |
4 |
14 |
44.0 |
3 |
F |
6 |
| 45 |
5 |
14.3 |
45.0 |
|
|
7 |
| 46 |
6 |
14.7 |
46.1 |
3.5 |
G |
8 |
| 47 |
7 |
15 |
47.1 |
4 |
H |
9 |
| 48 |
8 |
15.3 |
48.2 |
4.5 |
I |
10 |
| 49 |
9 |
15.7 |
49.2 |
5 |
J |
11 |
| 50 |
10 |
16 |
50.3 |
5.5 |
K |
12 |
| 51 |
11 |
16.3 |
51.3 |
6 |
L |
13 |
| 52 |
12 |
16.7 |
52.4 |
6.5 |
M |
14 |
| 53 |
13 |
17 |
53.4 |
7 |
N |
15 |
| 54 |
14 |
17.3 |
54.5 |
7.5 |
O |
16 |
| 55 |
15 |
17.7 |
55.5 |
8 |
P |
17 |
| 56 |
16 |
18 |
56.6 |
|
|
18 |
| 57 |
17 |
18.3 |
57.6 |
8.5 |
Q |
19 |
| 58 |
18 |
18.7 |
58.6 |
9 |
R |
20 |
| 59 |
19 |
19 |
59.7 |
9.5 |
S |
21 |
| 60 |
20 |
19.3 |
60.7 |
|
|
22 |
| 61 |
21 |
19.7 |
61.8 |
10 |
T |
23 |
| 62 |
22 |
20 |
62.8 |
10.5 |
U |
24 |
| 63 |
23 |
20.3 |
63.9 |
11 |
V |
25 |
| 64 |
24 |
20.7 |
64.9 |
11.5 |
W |
26 |
| 65 |
25 |
21 |
66.0 |
12 |
X |
27 |
| 66 |
26 |
21.3 |
67.0 |
12.5 |
Y |
28 |
| 67 |
27 |
21.7 |
68.0 |
13 |
Z |
29 |
