1. Standards for height and weight of 4-year-old babies At the age of 4, the height and weight of the baby are a very important indicator. According to the World Health Organization (WHO), the average height of 4-year-old boys is 101.8 cm and the average weight is 17.9 kg; the average height of 4-year-old girls is 100.5 cm and the average weight is 17.2 kg. Of course, this is only a rough reference value and may vary in actual situations. 2. How to measure the height and body of a 4-year-old baby