The weight of an eight-year-old boy should be 22.2-30.0 kilograms, and his height is 121.6-132.2 centimeters, which is normal within this range. (1) Children’s height: (1) Newborn length: 50 centimeters; (2) Infancy length: 75 centimeters; (3) Length over 1 year old: 5 x age + 75 centimeters, with a general range of 10% up and down. (4) Adult height: the heritability of height is 0.75, which means that 75% of adult height depends on heredity, and only 25% on factors such as exercise, nutrition, environment and social factors. Generally speaking, those with taller parents have taller children; those with shorter parents have shorter children. The adult height of a son (cm) = (father’s height + mother’s height) divided by 2 times 1.08; the adult height of a daughter (cm) = (father’s height times 0.923 + mother’s height) divided by 2. 2, the child’s weight: (1) 1-6 months weight (kg) = newborn weight + (0.6 × age); (2) 6-12 months weight (kg) = newborn weight + (0.5 × age); (3) 2-10 years weight (kg) = age 10 years of age weight (kg) = age x 2 + 7, with a general range of 10% up and down. When your child is growing up, you should pay attention to a balanced diet and supplement enough nutrients to help your child’s development and growth. Eat more food rich in vitamin C, vitamin A, vitamin D, vitamin B, calcium and protein, or pay attention to taking nutrients. If your child’s height or weight is not within the normal range, you need to go to the hospital to see if it is due to disease or lack of certain elemental substances, and you need to save the child in time or take nutritional supplements.