Ring Sizes Around ISO 48
| US | UK | ISO / EU | JP / KR | Diameter (mm) | Circumference (mm) |
| 3 | F | 44 | 4 | 14.1 | 44.2 |
| 3.5 | G | 46 | 5 | 14.5 | 45.5 |
| 4 | H | 47 | 7 | 14.9 | 46.8 |
| 4.5 | I | 48 | 8 | 15.3 | 48 |
| 5 | J | 49 | 9 | 15.7 | 49.3 |
| 5.5 | K | 51 | 10 | 16.1 | 50.6 |
| 6 | L | 52 | 12 | 16.5 | 51.9 |
Frequently Asked Questions
Does ISO 48 round up or down in UK?
Clear the knuckle and let the base settle; if you fall between 48 and 49, the larger reads easier over the joint and can be padded at the base later.
See a number that looks off? Report an error on this page.