Ring Size Converter — Formule
## Ring Size Conversion
Ring sizes vary by country. The US system uses numbers (typically 3-16), while the UK uses letters and EU uses circumference in mm minus 40.
### Approximate Formula
**Diameter (mm) = 11.63 + (US Size - 3) x 0.814**
**Circumference = Diameter x pi**
**EU Size = Circumference - 40**
### Quick Reference
| US | Diameter (mm) | EU |
|---|---|---|
| 5 | 15.7 | 49 |
| 7 | 17.3 | 54 |
| 9 | 19.0 | 60 |
Ring sizes vary by country. The US system uses numbers (typically 3-16), while the UK uses letters and EU uses circumference in mm minus 40.
### Approximate Formula
**Diameter (mm) = 11.63 + (US Size - 3) x 0.814**
**Circumference = Diameter x pi**
**EU Size = Circumference - 40**
### Quick Reference
| US | Diameter (mm) | EU |
|---|---|---|
| 5 | 15.7 | 49 |
| 7 | 17.3 | 54 |
| 9 | 19.0 | 60 |
Exemple Résolu
Convert US size 7 to other systems.
- Diameter = 11.63 + (7-3) x 0.814 = 14.886 mm
- Wait, let me recalculate: 11.63 + 4 x 0.814 = 14.886 mm
- Circumference = 14.886 x pi = 46.76 mm
- EU size = 46.76 - 40 = ~7