What is BMI?
Body Mass Index (BMI) is a simple measure of body fat based on height and weight. It is calculated as weight in kilograms divided by the square of height in meters.
For example, a person weighing 70 kg with a height of 1.75 m has a BMI of 70 ÷ (1.75 × 1.75) = 22.9.
BMI Categories
For adults, BMI is classified as: below 18.5 underweight, 18.5–24.9 normal weight, 25–29.9 overweight, and 30 or above obese. For the Indian population, many health experts suggest a lower cut-off of 23 for overweight.
A BMI in the normal range is associated with lower risk of diabetes, heart disease, and joint problems. Both very low and very high BMI carry health risks.
What BMI Doesn't Tell You
BMI does not distinguish between muscle and fat. A muscular athlete can have a high BMI with very low body fat, while a person with normal BMI can still have unhealthy visceral fat.
BMI also doesn't account for age, gender, or where fat is distributed. Waist circumference and body fat percentage give a more complete picture alongside BMI.
Track Your BMI Over Time
The most useful way to use BMI is as a trend: track it monthly along with your weight. A steady move from 27 toward 24 is a meaningful health improvement, even if you're not yet in the normal range.
Use our BMI calculator to check your number instantly, and pair it with a calorie calculator if your goal is to lose or gain weight.