US: 9-B to United Kingdom Size 6-AA

US: 9-B: Corresponds to a foot length of 26.2 $\text{cm}$ (10.31 $\text{in}$), ball width of 9.9 $\text{cm}$ (3.9 $\text{in}$), acceptable ball width range between 9.6–10.1 $\text{cm}$ (3.78–3.98 $\text{in}$), and fit classification Narrow (9-B / AA).

United Kingdom Size 6-AA: Corresponds to a foot length of 23.8 $\text{cm}$ (9.35 $\text{in}$), ball width of 9 $\text{cm}$ (3.5 $\text{in}$), acceptable ball width range between 8.8–9.2 $\text{cm}$ (3.45–3.6 $\text{in}$), and fit classification Extra Narrow (7-3A / AAAA).