Convert ring sizes between US, UK, EU systems plus diameter and circumference in millimeters.
| US | UK | EU | Diameter mm (mm) | Circumference mm (mm) |
|---|---|---|---|---|
| 3 | F | 44 | 14.0 | 44.2 |
| 3.5 | G | 45.5 | 14.4 | 45.5 |
| 4 | H | 46.5 | 14.8 | 46.8 |
| 4.5 | I | 47.8 | 15.2 | 48.0 |
| 5 | J½ | 49.3 | 15.7 | 49.3 |
| 5.5 | K½ | 50.6 | 16.1 | 50.6 |
| 6 | L½ | 51.5 | 16.5 | 51.9 |
| 6.5 | M½ | 53 | 16.9 | 53.1 |
| 7 | N½ | 54 | 17.3 | 54.4 |
| 7.5 | O½ | 55.7 | 17.7 | 55.7 |
| 8 | P½ | 56.6 | 18.1 | 57 |
| 8.5 | Q½ | 57.8 | 18.5 | 58.3 |
| 9 | R½ | 58.9 | 18.9 | 59.5 |
| 9.5 | S½ | 60.2 | 19.4 | 60.8 |
| 10 | T½ | 61.4 | 19.8 | 62.1 |
| 10.5 | U½ | 62.7 | 20.2 | 63.4 |
| 11 | V½ | 63.7 | 20.6 | 64.6 |
| 11.5 | W½ | 65 | 21.0 | 65.9 |
| 12 | Y | 66.1 | 21.4 | 67.2 |
| 13 | Z+1 | 68.5 | 22.2 | 69.7 |
Use the two dropdowns at the top to choose any "From" and "To" system. You can also click the swap button (⇄) between them to instantly reverse the conversion.
Size charts are based on standard manufacturer guidelines. However, actual fit can vary between brands. Always check the specific brand's size chart when possible.
Wrap a strip of paper around your finger, mark where it overlaps, and measure that length in millimeters. That's your circumference. Pick the matching size from the chart above.