BMI is "Body Mass Index". It tells you whether your body weight is appropriate for your height. In Indians it is advisable that the BMI be not more than 22.9*

BMI = Weight in kilograms / (Height in meters) 2

BMI is a gross estimate for the amount of fat in your body. It tells you whether you need to lose weight or not. Not all adults who have a BMI in the range labelled "healthy"are at their most healthy weight. They may have lots of fat but very little muscle. Similarly, if you are an athlete or exercise a lot, then you may have lots of muscle and less fat and if your BMI is more than the normal range, then it may still be healthy.

The BMI normal range is not applicable to pregnant and breast feeding mothers.