1. Height and weight standards for 3-year-old babies According to data from the World Health Organization, the average height of 3-year-old boys is 96.6 cm and weight is 15.3 kg; the average height of girls is 95.4 cm and weight is 14.7 kg. However, it should be noted that each child\’s growth and development is different, so this is only a rough reference value. 2. Factors affecting the baby\’s height and weight development 1. Genetic factors: Parental height, genetic genes, etc. will all affect the baby\’s height and weight development. 2. Diet: Malnutrition or overeating will have an impact on the baby\’s height and weight development.