Japanese and Chinese ring sizes with full conversion to US, UK, EU, and mm measurements.
Japan and China use a ring sizing system with numbers that are close to — but not identical with — the EU system. Japanese sizes (also called JIS sizes) run from approximately 1 to 30+ and are widely used across East Asia.
| Japan / China | US / Canada | UK / IRE / AUS | EU | Swiss | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|---|
| 4 | 3 | F | 44 | 4 | 14.1 | 44.2 |
| 5 | 3.5 | G | 45 | 5 | 14.5 | 45.6 |
| 7 | 4 | H | 46.5 | 6.5 | 14.9 | 46.8 |
| 8 | 4.5 | I | 48 | 8 | 15.3 | 48.0 |
| 9 | 5 | J | 49 | 9 | 15.7 | 49.3 |
| 11 | 5.5 | K | 50.5 | 10.5 | 16.1 | 50.6 |
| 12 | 6 | L | 51.5 | 11.5 | 16.5 | 51.9 |
| 13 | 6.5 | M | 53 | 13 | 16.9 | 53.2 |
| 14 | 7 | N | 54 | 14 | 17.3 | 54.4 |
| 16 | 7.5 | O | 55.5 | 15.5 | 17.7 | 55.7 |
| 17 | 8 | P | 57 | 17 | 18.2 | 57.2 |
| 18 | 8.5 | Q | 58 | 18 | 18.5 | 58.2 |
| 19 | 9 | R | 59 | 19 | 18.9 | 59.3 |
| 21 | 9.5 | S | 61 | 21 | 19.4 | 61.0 |
| 22 | 10 | T | 62 | 22 | 19.8 | 62.2 |
| 24 | 10.5 | U | 63.5 | 23.5 | 20.2 | 63.5 |
| 25 | 11 | V | 65 | 25 | 20.7 | 65.0 |
| 26 | 11.5 | W | 66 | 26 | 21.1 | 66.2 |
| 28 | 12 | X | 67.5 | 27.5 | 21.5 | 67.5 |
| 29 | 12.5 | Y | 68.5 | 28.5 | 21.9 | 68.8 |
| 30 | 13 | Z | 70 | 30 | 22.3 | 70.1 |
| 31 | 14 | Z+2 | 71 | 31 | 22.7 | 71.3 |
Japanese ring sizes are standardised by the Japanese Industrial Standards (JIS B 4801) and run as integers with occasional half sizes. Unlike EU sizes (which equal the circumference in mm exactly), Japanese sizes follow a slightly different scale. For most practical purposes, Japanese size ≈ EU size − 38, though this formula is approximate and the table should be used for precision.
Note that average hand size varies by population. Japanese average sizes tend to be slightly smaller than US averages.
When purchasing rings from Japanese brands (including many popular fashion and luxury brands sold internationally), look for the Japanese size listed alongside or instead of US/EU sizes. Use the chart above to convert. Always confirm the sizing system being used with the retailer — some Japanese brands selling internationally may have adopted US or EU sizing for their international ranges.