Gilbert's boot size conversion for UK sizes 6–15. The manufacturer does not list foot length.
| UK | US | EU |
| 6 | 6.5 | 39 |
| 6.5 | 7 | 39.5 |
| 7 | 7.5 | 40 |
| 7.5 | 8 | 41 |
| 8 | 8.5 | 42 |
| 8.5 | 9 | 42.5 |
| 9 | 9.5 | 43 |
| 9.5 | 10 | 44 |
| 10 | 10.5 | 44.5 |
| 10.5 | 11 | 45 |
| 11 | 11.5 | 45.5 |
| 11.5 | 12 | 46 |
| 12 | 13 | 47 |
| 13 | 13.5 | 48 |
| 14 | 14.5 | 49 |
| 15 | 15.5 | 50 |
Source: Gilbert boot size chart