💍 Jewellery
55.7 mm Ring Size
A ring with an inner circumference of 55.7 mm measures US 7.5 (EU/ISO 56, UK O½, 17.7 mm diameter). Full cross-system table below.
Circumference 55.7 mm = US 7.5
Inner circumference ≈ 55.7 mm · diameter ≈ 17.7 mm · EU/ISO 56
Full cross-system equivalents for this ring size:
| US | UK | EU | JP | Circ (mm) | Diam (mm) |
|---|---|---|---|---|---|
| 6 | L½ | 52 | 11 | 51.9 | 16.5 |
| 6.5 | M½ | 53 | 12 | 53.1 | 16.9 |
| 7 | N½ | 54 | 14 | 54.4 | 17.3 |
| 7.5 | O½ | 56 | 15 | 55.7 | 17.7 |
| 8 | P½ | 57 | 16 | 57.0 | 18.1 |
| 8.5 | Q½ | 58 | 17 | 58.3 | 18.5 |
| 9 | R½ | 60 | 18 | 59.5 | 18.9 |
⚠️ UK letters vary by jeweller: half-letter conventions differ slightly between brands. The EU/ISO number equals the inner circumference in mm, so it's the most reliable cross-check. If between sizes, order the larger.
Need a different size? Use the live ring size converter to convert any value, including a mm measurement.
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