The most comprehensive ring size conversion chart on the internet — covering every major sizing system in one table.
Our ring size chart covers all major international sizing systems including US/Canada, UK/Ireland/Australia, European (EU/French/German), Japanese/Chinese, and Swiss standards. Every row includes inside diameter in millimetres and circumference in millimetres so you can verify any measurement against any system.
| US / Canada | UK / IRE / AUS | EU / French | Japan / China | Swiss | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 4 | 14.1 | 44.2 |
| 3.5 | G | 45 | 5 | 5 | 14.5 | 45.6 |
| 4 | H | 46.5 | 7 | 6.5 | 14.9 | 46.8 |
| 4.5 | I | 48 | 8 | 8 | 15.3 | 48.0 |
| 5 | J | 49 | 9 | 9 | 15.7 | 49.3 |
| 5.5 | K | 50.5 | 11 | 10.5 | 16.1 | 50.6 |
| 6 | L | 51.5 | 12 | 11.5 | 16.5 | 51.9 |
| 6.5 | M | 53 | 13 | 13 | 16.9 | 53.2 |
| 7 | N | 54 | 14 | 14 | 17.3 | 54.4 |
| 7.5 | O | 55.5 | 16 | 15.5 | 17.7 | 55.7 |
| 8 | P | 57 | 17 | 17 | 18.2 | 57.2 |
| 8.5 | Q | 58 | 18 | 18 | 18.5 | 58.2 |
| 9 | R | 59 | 19 | 19 | 18.9 | 59.3 |
| 9.5 | S | 61 | 21 | 21 | 19.4 | 61.0 |
| 10 | T | 62 | 22 | 22 | 19.8 | 62.2 |
| 10.5 | U | 63.5 | 24 | 23.5 | 20.2 | 63.5 |
| 11 | V | 65 | 25 | 25 | 20.7 | 65.0 |
| 11.5 | W | 66 | 26 | 26 | 21.1 | 66.2 |
| 12 | X | 67.5 | 28 | 27.5 | 21.5 | 67.5 |
| 12.5 | Y | 68.5 | 29 | 28.5 | 21.9 | 68.8 |
| 13 | Z | 70 | 30 | 30 | 22.3 | 70.1 |
| 14 | Z+2 | 71 | 31 | 31 | 22.7 | 71.3 |
Find your known ring size in any column and read across the row to find the equivalent size in any other system. If you only have a measurement in millimetres:
The US system uses numbers with half-size increments (3, 3.5, 4, 4.5…). It is the most widely used system in North America. Average women's size is 6; average men's size is 10.
The UK/IRE/AUS system uses letters of the alphabet (A through Z, then Z+1, Z+2, etc.). It is also used in South Africa and some parts of Asia. Each letter step represents approximately 1.25mm in circumference.
European sizes are based directly on the inner circumference in millimetres. EU size 52 = 52mm inner circumference. This makes the EU system the most logical — your finger measurement in mm is your ring size.
Japan and China use a numerical system that runs roughly parallel to EU sizing but with different numbers. Japanese sizes are sometimes referred to as "JIS sizes." Chinese sizing follows the same scale.
Swiss sizing equals the inner diameter in mm minus 40. So a 17mm diameter ring = Swiss size 17. This system is less common internationally but used by some Swiss and German jewellers.
Before using this chart, ensure your measurement was taken correctly: