Body Mass Index (BMI) is the most common screening tool for adult body-weight classification, computed as weight in kilograms divided by height in metres squared (or weight in pounds divided by height in inches squared, multiplied by 703 for the imperial form).
Free Body Mass Index calculator gives out the BMI value and categorizes BMI based on provided information from WHO and CDC for both adults and children.

BMI, or Body Mass Index, is a measurement that assesses your body weight relative to your height. The BMI measurement can be used for any age, from babies and children to teens and adults.

Body mass index (BMI) is a calculated measure of weight relative to height. For adults, BMI is categorized into underweight, healthy weight, overweight, and obesity. Obesity is further subdivided into three classes. This BMI calculator is for adults 20 and older.
For example: Body builders-- Because muscle weighs more than fat, people who are very muscular may have a high BMI.The BMI only tells part of the story. Older adults with a normal BMI may have less muscle compared to others who are slightly overweight.