Body mass index (BMI) is a measurement of body fat based on height and weight. Learn how to calculate BMI using the BMI formula and equation, as well as how to use the BMI calculator. BMI is a simple calculation that uses a person’s height and weight to designate a classification. The formula is BMI = kg/m 2; kg is a person’s weight in kilograms and m 2 is height in metres squared. This BMI calculator will give your estimated number. Enter your height and weight below, then click the Submit button. If your BMI is above 25, losing weight is a smart idea. How do I calculate my BMI? You can calculate BMI yourself with these steps: Multiply your weight in pounds by 703. Divide that answer by your height in inches (there are 12 inches in 1 foot). Divide that answer by your height in inches again. This calculator provides BMI and the corresponding BMI category for adults 20 and older. For children and teens 2 through 19 years, use the BMI Calculator for Children and Teens. Use the interactive BMI formula calculator below to demonstrate the formula and resulting BMI calculation for your chosen weight and height figures. Options for both metric and imperial units are available. 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. Check an adult's or child's BMI to find out if they're a healthy weight. It's important to use the right calculator for adults (aged 18 and over) or children and teenagers (aged between 2 and 17). To calculate your body mass index (BMI), start by measuring your height in meters and then squaring it. Then, divide your weight in kilograms by your height in meters squared to find your BMI. BMI Calculator for men, women and children finds Body Mass Index given weight and height. BMI is a ratio of weight and height that indicates health risk due to overweight conditions.