Ring Size Conversion Chart
| Japan | US | UK/AU | ⌀ (mm) | ↻ (mm) |
|---|---|---|---|---|
| 1 | 1 | C | 13 | 40.8 |
| 2 | 2 | D | 13 1/3 | 41.9 |
| 3 | 2.5 | E | 13 2/3 | 42.9 |
| 4 | 3 | F | 14 | 44 |
| 5 | 3.5 | G | 14 1/3 | 45 |
| 6 | 3.5-4 | G-H | 14 2/3 | 46.1 |
| 7 | 4 | H-I | 15 | 47.1 |
| 8 | 4.5-5 | I-J | 15 1/3 | 48.2 |
| 9 | 5 | J | 15 2/3 | 49.2 |
| 10 | 5.5 | K | 16 | 50.3 |
| 11 | 6 | L | 16 1/3 | 51.3 |
| 12 | 6.5 | L-M | 16 2/3 | 52.4 |
| 13 | 6.5-7 | M-N | 17 | 53.4 |
| 14 | 7-7.5 | N-O | 17 1/3 | 54.5 |
| 15 | 7.5-8 | O-P | 17 2/3 | 55.5 |
| 16 | 8 | P | 18 | 56.6 |
| 17 | 8.5 | Q | 18 1/3 | 57.6 |
| 18 | 9 | R | 18 2/3 | 58.6 |
| 19 | 9.5 | S | 19 | 59.7 |
| 20 | 10 | T | 19 1/3 | 60.7 |
| 21 | 10-10.5 | T-U | 19 2/3 | 61.8 |
| 22 | 10.5 | U | 20 | 62.8 |
| 23 | 11 | V | 20 1/3 | 63.9 |
| 24 | 11.5 | W | 20 2/3 | 64.9 |
| 25 | 12 | X | 21 | 66 |
* Sizes are based on Japanese standards and may vary slightly depending on ring design and width. Please use as a guide only.