Ring Size Conversion Chart
| UK | US | Japan | Europe | Diameter | Circumference | |
| (mm) | (mm) | |||||
| H½ | 4 | 7 | 6 | 14.8 | 46.5 | |
| I½ | 4½ | 8 | 8 | 15.2 | 48 | |
| J½ | 5 | 9 | 9 | 15.6 | 49 | |
| L | 5½ | 10 | 10 | 16 | 50.5 | |
| M | 6 | 12 | 12 | 16.4 | 52 | |
| N | 6½ | 13 | 13 | 16.8 | 53 | |
| O | 7 | 14 | 14 | 17.3 | 54.5 | |
| P | 7½ | 15 | 15 | 17.7 | 55.5 | |
| Q | 8 | 16 | 17 | 18.1 | 57 | |
| Q½ | 8½ | 17 | 18 | 18.5 | 58 | |
| R½ | 9 | 18 | 19 | 18.9 | 59.5 | |
| S½ | 9½ | 20 | 21 | 19.3 | 61 | |
| T½ | 10 | 21 | 22 | 19.7 | 62 | |
| U½ | 10½ | 22 | 23 | 20.1 | 63.5 | |
| V½ | 11 | 24 | 24 | 20.6 | 64.5 | |
| W½ | 11½ | 25 | 26 | 21 | 66 | |
| Y | 12 | 26 | 27 | 21.4 | 67.5 | |
| Z | 12½ | 27 | 28 | 21.8 | 68.5 | |
| Z+1 | 13 | 28 | 30 | 22.2 | 70 | |
| Z+2 | 13½ | 29 | 31 | 22.6 | 71 | |
| Z+3 | 14 | 31 | 32 | 23 | 72.5 | |
| Z+4 | 14½ | 32 | 34 | 23.4 | 74 | |
| Z+5 | 15 | 33 | 35 | 23.9 | 75 |