Adult head circumference is about 54~58 centimeters. Measurement of head circumference: The measurement is made with a soft tape measure that is level with the upper edge of the eyebrows, opposite the occipital nodes at the back, and encircling the circumference of one’s head. It varies from person to person and is closely related to genetics, race, etc. Adults have a head circumference in the range of 54 to 58 centimeters. Head circumference is closely related to the development of the brain and skull. If the head circumference is too large and accompanied by vomiting and irritability, you should pay attention to the possibility of hydrocephalus; if the head circumference is too small, you should consider that it may be a case of underdevelopment of the brain or microcephaly, etc. Generally speaking, if there are no other uncomfortable symptoms, it is not necessary for the patient to have a head circumference. Generally speaking, if there are no other uncomfortable symptoms, a slightly larger or smaller head circumference is normal. If accompanied by vomiting, irritability, consciousness disorder, mental retardation, etc., we should be highly vigilant and actively go to the hospital for examination and treatment, so as to avoid delaying the condition.