To measure your head at home take a measuring tape around the circumference of your head. Keep it a fingers width above your ear and around where you like your hat to sit on your forehead. Make sure you are measuring around the largest part of the back of your head. Do not measure too tightly, we want your hat to fit comfortably. Below is a chart with sizes in inches and centimeters, translated into hat sizes. Feel free to tell me your size in any of the measurements (inches, centimeters, or hat size) Just make sure you are extreamly clear as to which one you are referring to.