Discover easy to use and free BMI Calculator App and Weight Tracker. The Body Mass Index (BMI) is calculated with the standard formula used by WHO (World Health Organization). Please note that age and gender DO NOT affect BMI calculation. What is BMI? Body mass index, or BMI, is used to determine whether you are in an ideal weight range for your height. Accurate BMI Calculator - check your ideal weight. It gives you an idea of whether you're "underweight", a "healthy weight", "overweight",