About BMI for Children and Teens
Follow these guidelines when taking height and weight measurements at home:
- Measuring Height Accurately At Home
- Measuring Weight Accurately At Home
- Child and Teen BMI Calculator
To measure height accurately at home to calculate BMI-for-age:
- Remove the child or teen's shoes, bulky clothing, and hair ornaments, and unbraid hair that interferes with the measurement.
- Take the height measurement on flooring that is not carpeted and against a flat surface such as a wall with no molding.
- Have the child or teen stand with feet flat, together, and against the wall. Make sure legs are straight, arms are at sides, and shoulders are level.
- Make sure the child or teen is looking straight ahead and that the line of sight is parallel with the floor.
- Take the measurement while the child or teen stands with head, shoulders, buttocks, and heels touching the flat surface (wall). (See illustration.) Depending on the overall body shape of the child or teen, all points may not touch the wall.
- Use a flat headpiece to form a right angle with the wall and lower the headpiece until it firmly touches the crown of the head.
- Make sure the measurer's eyes are at the same level as the headpiece.
- Lightly mark where the bottom of the headpiece meets the wall. Then, use a metal tape to measure from the base on the floor to the marked measurement on the wall to get the height measurement.
- Accurately record the height to the nearest 1/8th inch or 0.1 centimeter.
To measure weight accurately at home to calculate BMI-for-age:
- Use a digital scale. Avoid using bathroom scales that are spring-loaded. Place the scale on firm flooring (such as tile or wood) rather than carpet.
- Have the child or teen remove shoes and heavy clothing, such as sweaters.
- Have the child or teen stand with both feet in the center of the scale.
- Record the weight to the nearest decimal fraction (for example, 55.5 pounds or 25.1 kilograms).