A 13-year-old is typically 100.5 pounds in weight. 5 feet, 1 inch tall, or 61.6 inches tall, is the average height. 13-year-olds had an average waist size of 68 cm, or 26.7 inches.
Even at such an early age, boys and girls have differing weight-to-height ratios. The typical 13-year-old girl weighs 101 pounds, compared to 100 pounds for her male counterpart. Females are slightly taller and heavier than boys at this age.
Boys average 61.5 cm in height, compared to girls’ 61.7 centimetres. The average waist size of 13-year-old boys is 70.5 centimetres, or 27.7 inches, while that of girls is 65.5 centimetres, or 25.7 inches.