We prefer that you measure your head in centimeters because it tends to be more accurate than inches. Measure several times to ensure accuracy.
To measure your head size where your hat will sit, gather a cloth measuring tape or a simple string.
Start at the back of your head by gently wrapping the measuring tape or string towards your forehead a half inch (temple area) above your ears. Meet both ends of the measuring tape or string at the center of your forehead above the eyebrows.
Mark where those two points meet and measure the distance between the start and end points. If using a string, measure the start and end points against a ruler to find your hat size. Use this measurement to determine your hat size. Hat sizes vary by style, so be sure to check the unique fit for each.