A BMI Calculator is a tool used to determine a person's Body Mass Index (BMI), which is a measure of body fat based on height and weight. It helps assess whether an individual is underweight, normal weight, overweight, or obese. The formula for calculating BMI is weight in kilograms divided by height in meters squared. Using a BMI Calculator is straightforward. Users input their weight and height, and the calculator provides the BMI value along with a corresponding category. This information can be useful for individuals looking to maintain a healthy lifestyle or for healthcare professionals assessing a patient's health risks.