A 13-year-old child typically weighs 100.5 pounds. The average height is 5 feet and 1 inch, or 61.6 inches. The average waist circumference of 13-year-olds measures 68 centimetres (26.7 inches).
Even at an early age, males and girls have distinct weight-to-height ratios. The average female 13-year-old weighs 101 pounds, whereas the average man weighs 100 pounds. Women are slightly taller and heavier than men at this age. While girls average 61.7 centimetres in height, boys average 61.5 cm. The average waist size of 13-year-old boys is 70.5 centimetres or 27.7 inches, whereas the average waist size of 13-year-old girls is 65.5 centimetres or 25.7 inches.