CDC Vital Signs. Flash Player 9 or above is required. Follow us on Facebook BMI calculator Underweight < 19 Normal Weight 19 - 24.99 Overweight 25 - 29.99 Obese 30 - 39.99 Morbidly Obese - greater than or equal to 40. The BMI is determined with the formula weight divided by body height in meter to square. To make it easy for visitor of ....