The Tonus BMI and Growth Calculator is the first portable digital tool to use at home with your children, to calculate BMI and BMI percentiles, as well as their height and weight percentiles. You only need to know your childs height, weight, and age. Why wait a whole year to get the most important information about your child? One button with 4 positions controls all functions and entries.If you are concerned about your childs results, please contact your childs doctor and enquire if other health assessments or diagnostic tests should be performed. Doctors and other health care professionals are the best people to determine whether your childs weight is healthy, and they can help rule out rare medical problems as the cause of unhealthy weight. A physician will also consider your childs age and growth patterns to determine whether his or her weight is healthy.This product is designed to deliver the best results for children ages 2-18 and under 220 lbs (100 kg).