Body Mass Index (BMI) compares your weight with your height. It is the most widely used first check for whether an adult may be underweight, at a healthy weight, overweight or obese. This calculator works in metric (kg, cm) or imperial (lb, ft/in) units. It shows your BMI under the WHO international categories and the lower cut-offs recommended for Asian Indians, along with the healthy weight range for your height.
How to use the BMI calculator
- Choose Metric or Imperial units.
- Enter your height (cm, or feet and inches) and weight (kg or lb).
- Press Calculate BMI. You will see your BMI, its category and the weight range that would put you in the healthy band.
BMI formula
Imperial: BMI = 703 × weight (lb) ÷ [height (in)]²
Worked examples
- 170 cm, 72 kg: 72 ÷ (1.70 × 1.70) = 72 ÷ 2.89 = 24.9. That is “normal” on the WHO scale but “overweight” on the Asian-Indian scale.
- 5 ft 6 in (66 in), 160 lb: 703 × 160 ÷ 66² = 25.8. That is overweight on the WHO scale.
BMI categories: WHO vs Asian-Indian
People of South Asian origin tend to carry more body fat, especially around the abdomen, at the same BMI as Europeans, and develop type 2 diabetes and heart disease at lower BMIs. India’s 2009 consensus guidelines (endorsed by bodies including AIIMS and the Indian Council of Medical Research) and the WHO expert consultation for Asian populations therefore recommend lower thresholds:
| Category | WHO (international) | Asian-Indian guidelines |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Normal | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight | 25.0 – 29.9 | 23.0 – 24.9 |
| Obese | 30.0 and above | 25.0 and above |
If you are of Indian, Pakistani, Bangladeshi or Sri Lankan origin, the Asian-Indian cut-offs give a more accurate picture of your risk.
Healthy weight for your height
| Height | Healthy range (WHO 18.5–24.9) | Healthy range (Asian 18.5–22.9) |
|---|---|---|
| 150 cm (4′11″) | 41.6 – 56.0 kg | 41.6 – 51.5 kg |
| 155 cm (5′1″) | 44.4 – 59.8 kg | 44.4 – 55.0 kg |
| 160 cm (5′3″) | 47.4 – 63.7 kg | 47.4 – 58.6 kg |
| 165 cm (5′5″) | 50.4 – 67.8 kg | 50.4 – 62.3 kg |
| 170 cm (5′7″) | 53.5 – 72.0 kg | 53.5 – 66.2 kg |
| 175 cm (5′9″) | 56.7 – 76.3 kg | 56.7 – 70.1 kg |
| 180 cm (5′11″) | 59.9 – 80.7 kg | 59.9 – 74.2 kg |
| 185 cm (6′1″) | 63.3 – 85.2 kg | 63.3 – 78.4 kg |
Limitations of BMI
- Muscle vs fat: muscular people such as athletes and bodybuilders can have a “high” BMI with low body fat.
- Where fat is stored: belly fat is riskier than fat on the hips and thighs, and BMI cannot tell them apart. Also measure your waist. Indian guidelines flag risk above 90 cm for men and 80 cm for women.
- Age: older adults lose muscle, so a “normal” BMI may hide low muscle mass. Some experts accept a slightly higher BMI as healthy after 65.
- Children and teens: under-18s must use BMI-for-age percentile charts (WHO or IAP growth charts), not the adult categories above.
- Pregnancy: BMI is not meaningful during pregnancy. Doctors use pre-pregnancy BMI to guide weight gain.
Other measures to use alongside BMI
- Waist-to-height ratio: keep your waist under half your height. A ratio of 0.5 or more suggests raised cardiometabolic risk.
- Waist-to-hip ratio: above 0.90 (men) or 0.85 (women) indicates central obesity.
- Body-fat percentage: from DEXA, skinfold callipers or bioimpedance scales. Home scales vary in accuracy.
If your BMI is outside the healthy range
A gradual change of 0.25–0.5 kg a week is sustainable for most adults. Use the Calorie Calculator to set a daily target, and the BMR Calculator to understand your resting energy needs. A BMI below 18.5 can also signal nutritional problems that need medical attention.
References: World Health Organization BMI classification; WHO Expert Consultation, “Appropriate body-mass index for Asian populations”, The Lancet, 2004; Misra A. et al., “Consensus statement for diagnosis of obesity, abdominal obesity and the metabolic syndrome for Asian Indians”, JAPI, 2009.
Frequently asked questions
How is BMI calculated?
BMI = weight in kg ÷ (height in metres)². A person 1.70 m tall weighing 72 kg has a BMI of 72 ÷ 2.89 = 24.9. In pounds and inches, multiply by 703: BMI = 703 × lb ÷ in².
What is a normal BMI for Indians?
Indian guidelines consider 18.5–22.9 normal, 23–24.9 overweight and 25 or above obese. These cut-offs are lower than the WHO international ones because South Asians face higher metabolic risk at the same BMI.
What is the ideal weight for 5 feet 6 inches?
For 168 cm, the WHO healthy range is about 52–70 kg, and the Asian-Indian range is about 52–65 kg. The table on this page lists ranges for other heights.
Is BMI accurate for athletes?
Not very. BMI cannot tell muscle from fat, so muscular people often score “overweight” despite low body fat. Waist measurement or body-fat testing gives a better picture.
Can I use this BMI calculator for children?
No. Children and teenagers need age- and sex-specific BMI percentile charts. Use the WHO or Indian Academy of Pediatrics growth charts, or ask a paediatrician.