BMI Calculator

BMI stands for body mass index. It is a number calculated from weight and height that helps classify adults into broad weight categories. BMI is useful as a quick screening tool because it is easy to calculate and compare, but it does not directly measure body fat, muscle mass, bone density, or overall fitness.

For most adults, a BMI from 18.5 to 24.9 is considered the normal or healthy weight range. A BMI below 18.5 is classified as underweight, while 25.0 to 29.9 is overweight. A BMI of 30 or above is classified as obesity. Individual health risk should be assessed with other medical factors too.

BMI is not equally accurate for every person. It can overestimate body fat in athletes or muscular people and underestimate risk in people with low muscle mass. It also does not account for waist size, age, sex, ethnicity, pregnancy, or medical conditions. Use BMI as a screening number, not a diagnosis.

In metric units, BMI equals weight in kilograms divided by height in meters squared. The formula is BMI = kg / m². In imperial units, BMI equals weight in pounds divided by height in inches squared, multiplied by 703. Both formulas produce the same body mass index scale.

Lowering BMI usually means reducing body weight relative to height through sustainable nutrition, regular physical activity, better sleep, and consistent habits. Small calorie deficits, strength training, and walking can help many people. If your BMI is very high or you have medical conditions, speak with a qualified healthcare professional before starting major changes.