Head circumference is measured by using a soft tape measure around the head, passing over the arch of the eyebrow and the highest point of the occipital bone. The head circumference is measured using a soft tape measure that passes over the arches of the eyebrows on both sides, over the upper edge of the auricles on both sides and over the occipital bone at the back (i.e., the highest point), when the head circumference can be measured accurately. The average newborn’s head circumference is around 34 centimeters. With growth, children’s head circumference gradually grows, in two years old can reach about 48 centimeters, after that the head circumference growth gradually slows down, in five years old to reach about 50 centimeters. Head circumference is measured to determine whether a person’s skull and brain development have reached normal standards. Head circumference usually stops growing and reaches the adult standard at around 15 years of age. A small head circumference may be seen as a deformity that hinders brain development. Large head circumference can be seen in hydrocephalus and rickets. Any abnormality in the measurement of head circumference requires prompt medical attention.