Europe Size 54 to US: 3-6M

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: 3-6M: Corresponds to a head circumference baseline of 41 $\text{cm}$ (16.1 $\text{in}$) and age range 3–6 $\text{months}$.