Ask any adult in your family if they know their hat size. Then, get some string and a tape measure or ruler.

To determine their hat size, use the string to measure the circumference or length around the head. Place the string where a hat would normally rest (above the eyebrows and ears.) Do not pull the string too tight.

Mark or cut the string to the length that you measured. Lay the string beside a tape measure or ruler to see the inches. Compare the inches to the hat sizes on the graph.