Size Chart for Rings
| US | AU& UK | EU | Diameter (mm/inches) |
| 4.5 | I 1/2 | 48mm |
15.2mm/ 1 7/8 inches |
| 5 | J 1/2 | 49mm |
15.7 mm/ 1 15/16 inches |
| 5.5 | L | 51mm |
16.1mm/ 2 inches |
| 6 | M | 52mm |
16.5 mm/ 2 1/16 inches |
| 6.5 | N | 53mm |
16.9 mm/ 2 1/8 inches |
| 7 | O | 55mm |
17.3 mm/ 2 3/16 inches |
| 7.5 | P | 56mm |
17.7 mm/ 2 1/4 inches |
| 8 | Q | 57mm |
18.1 mm/ 2 5/16 inches |
| 8.5 | Q 1/2 | 58mm |
18.5mm/ 2 3/8 inches |
| 9 | R 1/2 | 59mm |
18.8 mm/ 2 7/16 inches |
| 9.5 | S 1/2 | 61mm |
19.4 mm/ 2 1/2 inches |
| 10 | T 1/2 | 62 mm |
19.8mm/ 2 9/16 inches |
| 10.5 | U 1/2 | 63mm |
20.2 mm/ 2 5/8 inches |
| 11 | V 1/2 | 65mm |
20.6 mm/ 2 11/16 inches |
| 11.5 | W 1/2 | 66mm |
21 mm/ 2 3/4 inches |
| 12 | Y | 68mm |
21.4 mm/ 2 13/16 inches |
| 12.5 | Z | 69mm |
21.89 mm/ 2 7/8 inches |
| 13 | - | 70mm |
22.3mm/ 2 15/16 inches |