Height standard for three-year-old children Measuring a child\’s height is one of the important means of judging his or her physical development. For three-year-olds, height is measured differently than for adults and teenagers. Below we will discuss the height standards for three-year-old children from several aspects and how to correctly measure the child\’s height. 1. Height standard for three-year-old children The height standard for three-year-old children is based on three factors: age, gender and height.