Help & Advice Ring Converter
Ring size equivalents
| UK | US | JAPAN | DIAMETER (mm) | CIRCUMFERENCE (mm) | EUROPE |
| H½ | 4 | 7 | 14.8 | 46.5 | 6 |
| I½ | 4½ | 8 | 15.2 | 48 | 8 |
| J½ | 5 | 9 | 15.6 | 49 | 9 |
| L | 5½ | 10 | 16 | 50.5 | 10 |
| M | 6 | 12 | 16.4 | 52 | 12 |
| N | 6½ | 13 | 16.8 | 53 | 13 |
| O | 7 | 14 | 17.3 | 54.5 | 14 |
| P | 7½ | 15 | 17.7 | 55.5 | 15 |
| Q | 8 | 16 | 18.1 | 57 | 17 |
| Q½ | 8½ | 17 | 18.5 | 58 | 18 |
| R½ | 9 | 18 | 18.9 | 59.5 | 19 |
| S½ | 9½ | 20 | 19.3 | 61 | 21 |
| T½ | 10 | 21 | 19.7 | 62 | 22 |
| U½ | 10½ | 22 | 20.1 | 63.5 | 23 |
| V½ | 11 | 24 | 20.6 | 64.5 | 24 |
| W½ | 11½ | 25 | 21 | 66 | 26 |
| Y | 12 | 26 | 21.4 | 67.5 | 27 |
| Z | 12½ | 27 | 21.8 | 68.5 | 28 |
| Z+1 | 13 | 28 | 22.2 | 70 | 30 |
| Z+2 | 13½ | 29 | 22.6 | 71 | 31 |
| Z+3 | 14 | 31 | 23 | 72.5 | 32 |
| Z+4 | 14½ | 32 | 23.4 | 74 | 34 |
| Z+5 | 15 | 33 | 23.9 | 75 | 35 |
NB ring-sizing systems do not convert exactly; the above is an approximated conversion for use as a guide only.