Body Mass Index (BMI) is one of the most widely used health screening tools, helping you understand whether your weight falls within a healthy range relative to your height. This BMI calculator works with both metric (kilograms and centimeters) and imperial (pounds, feet, and inches) units, instantly computing your BMI score and placing it into the standard WHO categories: underweight, normal weight, overweight, or obese. While BMI doesn't account for muscle mass or body composition directly, it remains a useful starting point for assessing weight-related health risks. Use this calculator to track changes over time or as a conversation starter with your healthcare provider.