Ring sizing chart
| British Size | Inside Diameter mm | USA Size | Inside Diameter mm | European Size | Inside Diameter mm |
|---|---|---|---|---|---|
| A | 11.97 | 0.5 | 11.97 | ||
| B | 12.36 | 1 | 12.37 | 1 | 13.04 |
| C | 12.75 | 1.5 | 12.78 | 2 | 13.36 |
| D | 13.14 | 2 | 13.21 | 3 | 13.67 |
| E | 13.53 | 2.5 | 13.61 | 4 | 13.99 |
| F | 13.92 | 3 | 14.05 | 5 | 14.31 |
| G | 14.31 | 3.5 | 14.45 | 6 | 14.63 |
| H | 14.70 | 4 | 14.86 | 7 | 14.95 |
| I | 15.09 | 4.5 | 15.27 | 8 | 15.27 |
| J | 15.48 | 5 | 15.70 | 9 | 15.58 |
| K | 15.87 | 5.5 | 16.10 | 10 | 15.90 |
| L | 16.26 | 6 | 16.51 | 11 | 16.22 |
| M | 16.65 | 6.5 | 16.92 | 12 | 16.54 |
| N | 17.04 | 7 | 17.35 | 13 | 16.86 |
| O | 17.45 | 7.5 | 17.75 | 14 | 17.17 |
| P | 17.86 | 8 | 18.19 | 15 | 17.49 |
| Q | 18.27 | 8.5 | 18.59 | 16 | 17.81 |
| R | 18.68 | 9 | 18.89 | 17 | 18.13 |
| S | 19.09 | 9.5 | 19.41 | 18 | 18.45 |
| T | 19.50 | 10 | 19.84 | 19 | 18.76 |
| U | 19.91 | 10.5 | 20.20 | 20 | 19.08 |
| V | 20.32 | 11 | 20.24 | 21 | 19.40 |
| W | 20.73 | 11.5 | 20.68 | 22 | 19.72 |
| X | 21.14 | 12 | 21.08 | 23 | 20.04 |
| Y | 21.55 | 12.5 | 21.49 | 24 | 20.35 |
| Z | 21.96 | 13 | 21.89 | 25 | 20.67 |
| 13.5 | 22.33 | 26 | 20.99 | ||
| 27 | 21.31 | ||||
| 28 | 21.63 | ||||
| 29 | 21.94 | ||||
| 30 | 22.26 |