BMI is a measure of body fat based on an individual's weight in relation to their height. The calculator takes the input of an individual's weight in kilograms or pounds, and height in meters or feet, and then calculates the BMI value. The BMI value is then interpreted to determine the individual's weight status, whether they are underweight, normal weight, overweight, or obese.

The BMI calculation is based on a formula that divides an individual's weight by the square of their height. The resulting number is then compared to a BMI chart that provides weight status categories. BMI is a useful tool for assessing an individual's risk of developing health problems related to being overweight or underweight, such as heart disease, diabetes, and certain cancers.
BMI Calculator apps have become increasingly popular as more people are becoming aware of the importance of maintaining a healthy weight. They are easy to use and can be accessed from a variety of devices, including smartphones and computers. Some BMI Calculator apps also provide additional features such as tracking weight loss progress and providing personalized recommendations for maintaining a healthy weight.