United Kingdom Size 6 1/2 to US: S

Cross-market women’s hat conversion mapping 6 1/2 specifications into S.

Analyzing Hat Size Equivalence Across Markets

United Kingdom Size 6 1/2: Features a head circumference of 53 $\text{cm}$ (20.9 $\text{in}$ ) measured just above the brow and ears.

US: S: Features a head circumference of 54.5 $\text{cm}$ (21.5 $\text{in}$ ) measured just above the brow and ears.