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What is BMI?
Body Mass Index (BMI) is a simple numerical measure of a person's body fat based on their weight and height. It is widely used by doctors and health professionals as a quick screening tool to classify adults as underweight, normal weight, overweight, or obese.
How to Use This BMI Calculator
- Enter your weight in kilograms (e.g., 70 kg).
- Enter your height in centimetres (e.g., 170 cm).
- Click Calculate to see your BMI and weight category.
BMI Formula
Example: 70 kg ÷ (1.70 m)² = 70 ÷ 2.89 = 24.2
BMI Categories
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Moderate risk of nutritional deficiency |
| 18.5 – 24.9 | Normal weight | Lowest health risk |
| 25.0 – 29.9 | Overweight | Increased risk |
| 30.0 and above | Obese | High risk of diabetes, heart disease |
BMI for South Asians
Research suggests that South Asians (including Indians) have a higher percentage of body fat at the same BMI compared to Caucasians. Many Indian health organisations recommend using lower cutoffs: overweight above 23, obese above 25 for the South Asian population.
How to Maintain a Healthy BMI
- Eat a balanced diet rich in vegetables, protein, and whole grains.
- Exercise at least 150 minutes per week (brisk walking, cycling, swimming).
- Limit processed foods, sugar, and refined carbohydrates.
- Stay hydrated — drink 2–3 litres of water daily.
- Get 7–8 hours of sleep per night, as poor sleep disrupts metabolism.
More Worked Examples
Here's how the same formula plays out at different heights and weights:
- 55 kg at 160 cm: 55 ÷ (1.60)² = 55 ÷ 2.56 = 21.5 (Normal weight)
- 85 kg at 175 cm: 85 ÷ (1.75)² = 85 ÷ 3.0625 = 27.8 (Overweight)
- 48 kg at 165 cm: 48 ÷ (1.65)² = 48 ÷ 2.7225 = 17.6 (Underweight)
Frequently Asked Questions
Is BMI accurate for everyone? No — it doesn't distinguish muscle from fat, so bodybuilders and athletes often show a "high" BMI despite low body fat. It also isn't designed for children, pregnant women, or the elderly.
What's a healthy BMI for Indians specifically? Because South Asians tend to carry more body fat at the same BMI as Europeans, many doctors in India treat 23–24.9 as "overweight" and 25+ as "obese" rather than the WHO's standard 25 and 30 cutoffs.
📅 Last reviewed: July 2026 · Formulas verified against RBI/SEBI/IT Dept guidelines.