Hat size

Hat sizes are determined by measuring the circumference of a person's head about 1/2 inch (1.3 cm) above the ears and dividing by pi. In the UK, an equivalent hat size is an eighth an inch smaller than in the US. [2] Inches or centimeters may be used depending on the manufacturer. Felt hats can be stretched for a custom fit, and hard hats (such as Derbys and top hats) have a hard goss which can be melted to adjust size. Cheaper hats come in standard sizes, such as small, medium, large. Some hats, like baseball caps, are adjustable