How To Know What Size Hat To Buy -
To get an accurate measurement, you will need a soft, flexible measuring tape. If you do not have one, you can use a piece of non-stretching string or ribbon and then measure that against a ruler later.
Place the measuring tape around your head, approximately 1/8 to 1/2 inch (0.3–1 cm) above your ears and across the middle of your forehead —exactly where the hat's sweatband will sit. how to know what size hat to buy
Most manufacturers categorize hats into "Generic" (S, M, L) or "Numerical" (US/UK) sizes based on the circumference you just measured. Measure Your Hat Size, Head Circumference To get an accurate measurement, you will need