Europe Size 54 to US: 18-24M

Europe Size 54: Corresponds to a head circumference baseline of 54 $\text{cm}$ (21.3 $\text{in}$) and age range 84–144 $\text{months}$.

US: 18-24M: Corresponds to a head circumference baseline of 48 $\text{cm}$ (18.9 $\text{in}$) and age range 18–24 $\text{months}$.