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BMI Calculator

Calculate your Body Mass Index (BMI) - the WHO standard for assessing healthy weight range by height.

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WHO BMI Categories

Underweight

BMI < 18.5

May indicate malnutrition, eating disorders or underlying illness. Consider consulting a doctor.

Normal Weight

BMI 18.5 – 24.9

Associated with the lowest health risks. Maintain through balanced diet and regular activity.

Overweight

BMI 25 – 29.9

Increased risk of heart disease, type 2 diabetes and hypertension. Weight loss recommended.

Obese

BMI ≥ 30

High health risk. Consult a healthcare professional for a personalised weight-management plan.

BMI Calculator

Body Mass Index (BMI) is a simple screening index calculated by dividing a person's weight in kilograms by the square of their height in metres (kg/m2). Developed by Belgian statistician Adolphe Quetelet in the 1830s, it was formally adopted by the WHO as a global obesity classification tool in the 1990s. The standard WHO categories are: Underweight (below 18.5), Normal (18.5-24.9), Overweight (25-29.9), and Obese (30+). This calculator supports both metric and imperial inputs and shows your healthy weight range for your height.

Lower Thresholds for Asian Indians

A landmark 2004 WHO expert consultation recommended lower BMI cutoff points for Asian populations. For South Asians, including Indians, overweight begins at 23 kg/m2 and obesity at 27.5 kg/m2, because Indians carry proportionally more abdominal fat at lower BMIs than Caucasians, raising cardiometabolic risk at seemingly normal weights. The ICMR and the Research Society for the Study of Diabetes in India (RSSDI) use these revised cutoffs in clinical guidelines. This is especially relevant given that India had an estimated 77 million people with diabetes in 2019 - second only to China globally - with obesity being a leading driver.

Frequently Asked Questions

BMI (Body Mass Index) is calculated from height and weight to indicate body fatness. WHO categories: Under 18.5 = Underweight; 18.5–24.9 = Normal; 25–29.9 = Overweight; 30+ = Obese. For Indians, ICMR recommends lower cutoffs - BMI above 23 is overweight and above 27.5 is obese, since Asians carry more body fat at a lower BMI.

BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat - a muscular athlete may be classified as overweight despite low body fat. It also does not account for fat distribution (visceral fat is more dangerous than subcutaneous fat). Always combine BMI with waist circumference, body fat percentage and blood work for a complete health picture.

For Indians and South Asians, health authorities including ICMR recommend lower BMI thresholds: 18–22.9 is normal, 23–24.9 is overweight, and 25 or above is obese. Indian populations tend to have higher body fat percentages and more visceral (abdominal) fat at any given BMI, increasing risk of type 2 diabetes and cardiovascular disease at lower BMI values.

BMI = Weight (kg) ÷ Height (m)². Example: if you weigh 70 kg and are 1.70 m tall, BMI = 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2. In imperial: BMI = (Weight in pounds × 703) ÷ (Height in inches)². Our calculator handles both metric and imperial units automatically.