BMI Categories — WHO and Indian Standards
The World Health Organisation (WHO) and the Indian Council of Medical Research (ICMR) use slightly different BMI cut-offs. This matters because research shows South Asians have higher health risks at lower BMI values compared to Western populations.
WHO Global Standards
| Category | BMI Range | Health Risk |
|---|---|---|
| Underweight | Below 18.5 | Increased risk of malnutrition and related conditions |
| Normal weight | 18.5 – 24.9 | Lowest health risk for general population |
| Overweight | 25.0 – 29.9 | Increased risk of cardiovascular disease and diabetes |
| Obese Class I | 30.0 – 34.9 | High risk — medical attention recommended |
| Obese Class II | 35.0 – 39.9 | Very high risk |
| Obese Class III | 40.0 and above | Extremely high risk |
ICMR Standards for Indians (Recommended)
| Category | BMI Range (Indian) | Difference from WHO |
|---|---|---|
| Underweight | Below 18.5 | Same as WHO |
| Normal weight | 18.5 – 22.9 | Lower upper limit (WHO: 24.9) |
| Overweight | 23.0 – 27.4 | Starts 2 points lower than WHO |
| Obese | 27.5 and above | Starts lower than WHO's 30.0 |
⚠️ Important for Indians: If your BMI is between 23 and 25, you may be classified as Normal by WHO standards but Overweight by ICMR guidelines. Indians at BMI 23+ have significantly higher risk of Type 2 diabetes and cardiovascular disease compared to Europeans at the same BMI. Consult your doctor for a complete assessment.
How to Use the BMI Calculator
- Choose your unit system — Metric (kg and cm) for most Indians, Imperial (pounds and inches) if you know your measurements in those units.
- Enter your weight and height — be as accurate as possible. Measure your height without shoes.
- Enter your age and gender — these are used to provide context since BMI interpretation varies with age.
- Click Calculate BMI — your BMI, category, healthy weight range, and Indian-specific interpretation appear instantly.
BMI Formula — How It Is Calculated
BMI is calculated by dividing your weight in kilograms by the square of your height in metres:
BMI = Weight (kg) ÷ Height² (m²)
For example, if you weigh 68 kg and are 165 cm (1.65 m) tall:
BMI = 68 ÷ (1.65 × 1.65) = 68 ÷ 2.7225 = 24.98
Converting height from feet and inches to cm
| Height (ft & in) | Height (cm) | Height (inches) |
|---|---|---|
| 5 ft 0 in | 152.4 cm | 60 in |
| 5 ft 2 in | 157.5 cm | 62 in |
| 5 ft 4 in | 162.6 cm | 64 in |
| 5 ft 6 in | 167.6 cm | 66 in |
| 5 ft 8 in | 172.7 cm | 68 in |
| 5 ft 10 in | 177.8 cm | 70 in |
| 6 ft 0 in | 182.9 cm | 72 in |
Limitations of BMI
BMI is a useful screening tool, but it has important limitations that everyone should understand:
- Does not distinguish muscle from fat: A muscular athlete may have a BMI in the overweight range despite having very low body fat. A sedentary person may have a normal BMI but high body fat (called "skinny fat" or normal-weight obesity).
- Does not account for fat distribution: Where you carry fat matters as much as how much you carry. Abdominal fat (belly fat) is significantly more dangerous than fat stored on the hips and thighs. Waist circumference is a better predictor of metabolic risk.
- Age differences: Older adults naturally have more body fat at the same BMI than younger adults. BMI may underestimate health risks in older people.
- Gender differences: Women naturally carry more body fat than men at the same BMI.
- Ethnic differences: As noted above, South Asians have higher health risks at lower BMI values than European populations.
💡 Better measurements to use alongside BMI: Waist circumference (healthy: under 80 cm for women, under 90 cm for men in India), waist-to-height ratio (healthy: under 0.5), and body fat percentage measured by a healthcare professional.
Healthy Weight Management Tips for Indians
India has one of the fastest-growing rates of obesity and Type 2 diabetes in the world. Here are evidence-based recommendations:
Diet
- Reduce refined carbohydrates — white rice, white bread, maida-based foods spike blood sugar rapidly
- Increase fibre — dal, vegetables, whole grains, and fruits slow digestion and improve satiety
- Watch portion sizes of rice and roti — these are calorie-dense and easy to overeat
- Limit fried foods, sweets, and packaged snacks — high in calories, low in nutrition
- Eat more protein — dal, paneer, eggs, fish, and chicken help preserve muscle and keep you full longer
Exercise
- WHO recommends at least 150 minutes of moderate activity per week — that is 30 minutes, 5 days a week
- Walking is the most accessible form of exercise and has significant health benefits at any BMI
- Strength training 2–3 times per week helps build muscle and improves metabolism
- Reduce sitting time — sedentary behaviour is independently associated with health risks regardless of exercise
Frequently Asked Questions
What is a normal BMI?
By WHO standards, a normal or healthy BMI is between 18.5 and 24.9. For South Asians including Indians, the ICMR recommends lower cut-offs: normal is 18.5–22.9, overweight starts at 23.0, and obese at 27.5. This is because research shows Indians have higher body fat and greater health risks at the same BMI compared to Western populations.
How is BMI calculated?
BMI = Weight (kg) ÷ Height² (m²). For example, if you weigh 70 kg and are 1.75 m tall: BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9. This falls in the normal range by both WHO and ICMR standards. For imperial units, the formula is: BMI = (Weight in pounds × 703) ÷ Height² (in inches²).
Is BMI accurate for Indians?
Standard WHO BMI categories were developed using primarily Western populations. Research consistently shows that South Asians, including Indians, have higher body fat percentage at the same BMI as Europeans, and develop diabetes and cardiovascular disease at lower BMI values. The ICMR therefore recommends that Indians treat BMI 23 as the overweight threshold rather than the WHO standard of 25.
Can BMI be misleading?
Yes. BMI does not distinguish between muscle and fat — a muscular person may have a high BMI but low body fat. It also does not account for where body fat is stored — abdominal fat is significantly more dangerous than fat on the hips and thighs. BMI is a population-level screening tool, not a diagnostic tool. Always consult a doctor for a complete health assessment that considers waist circumference, blood tests, and other factors.
What is the ideal BMI for an Indian adult?
According to ICMR guidelines, the ideal BMI for Indian adults is between 18.5 and 22.9. A BMI of 23.0–27.4 is classified as overweight, and 27.5 and above is obese for Indians. These thresholds are lower than WHO global standards because Indians have higher cardiometabolic risk at lower BMI values.
What is the BMI for a 70 kg person who is 5 feet 7 inches tall?
5 feet 7 inches = 170.18 cm = 1.7018 m. BMI = 70 ÷ (1.7018)² = 70 ÷ 2.896 = 24.2. This falls in the Normal weight range by WHO standards (18.5–24.9), but is classified as Overweight by ICMR standards for Indians (which sets the overweight threshold at 23.0). This highlights why the Indian context matters when interpreting BMI.