US: 12-D to United Kingdom Size 6-AA

US: 12-D: Corresponds to a foot length of 29 $\text{cm}$ (11.42 $\text{in}$), ball width of 10.8 $\text{cm}$ (4.25 $\text{in}$), acceptable ball width range between 10.5–11.1 $\text{cm}$ (4.13–4.37 $\text{in}$), and fit classification Standard Width (12-D / M).

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).