| US Size | Inside Diameter (mm) | Inside Circumference (mm) | UK & South Africa Equivalent |
| 5 | 15.7 | 49.3 | J ½ |
| 6 | 16.5 | 51.8 | L ½ |
| 7 | 17.3 | 54.4 | N ½ |
| 8 | 18.1 | 56.9 | P ½ |
| 9 | 18.9 | 59.5 | R ½ |
| 10 | 19.8 | 62.1 | T ½ |
| US Size | Inside Diameter (mm) | Inside Circumference (mm) | UK & South Africa Equivalent |
| 5 | 15.7 | 49.3 | J ½ |
| 6 | 16.5 | 51.8 | L ½ |
| 7 | 17.3 | 54.4 | N ½ |
| 8 | 18.1 | 56.9 | P ½ |
| 9 | 18.9 | 59.5 | R ½ |
| 10 | 19.8 | 62.1 | T ½ |