Calculate Your Body Mass Index. Body mass index (BMI) is a measure of body fat based on height and weight that applies to adult men and women. Enter your. Feb 22, - American women aged 20 years and above weigh an average of pounds (lbs), according to the Centers for Disease Control and Prevention (CDC). Height-wise, the average adult female is 5 feet 4 inches, and her waist measures inches. While these numbers may be the average, they are not a measure of health.Average weight · Ideal weight range · Other factors.