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.
The tape should be level and snug, but not tight. A good rule of thumb is to allow enough space for one finger to fit between your head and the tape. how to know what size hat to buy
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. To get an accurate measurement, you will need