What is BMI?
Body mass index (BMI) is your weight in kilograms divided by your height in metres squared. It is quick, free and needs no equipment, which is why doctors and public-health agencies use it to screen for weight-related health risk across large groups of people.
It is a screening number, not a diagnosis. BMI doesn't know whether your weight is muscle or fat, or where that fat is stored — which matters a lot for health.
BMI chart
| Category | International (WHO) | Indian / Asian cut-offs |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Healthy range | 18.5–24.9 | 18.5–22.9 |
| Overweight | 25–29.9 | 23–24.9 |
| Obesity | 30 and above | 25 and above |
Healthy weight ranges by height, on each scale:
| Height | Indian / Asian (18.5–22.9) | International (18.5–24.9) |
|---|---|---|
| 150 cm (4 ft 11 in) | 42–51 kg | 42–56 kg |
| 155 cm (5 ft 1 in) | 44–55 kg | 44–60 kg |
| 160 cm (5 ft 3 in) | 47–59 kg | 47–64 kg |
| 165 cm (5 ft 5 in) | 50–62 kg | 50–68 kg |
| 170 cm (5 ft 7 in) | 53–66 kg | 53–72 kg |
| 175 cm (5 ft 9 in) | 57–70 kg | 57–76 kg |
| 180 cm (5 ft 11 in) | 60–74 kg | 60–81 kg |
BMI for Indians and South Asians
At the same BMI, South Asians tend to carry more body fat — especially around the abdomen — and develop type 2 diabetes and heart disease at lower body weights than white Europeans. A WHO expert consultation in 2004 recognised this for Asian populations, and Indian consensus guidelines (2009) recommend treating a BMI of 23 or more as overweight and 25 or more as obesity for Asian Indians.
That is why this calculator shows both scales. If you are of South Asian heritage and your BMI is between 23 and 25, the international scale may call you “healthy” while the Indian cut-offs flag higher risk. It is a prompt to check your waist, activity and diet — not a cause for alarm.
Limitations of BMI
- Muscle: strength-trained people often score as “overweight” while being lean.
- Fat distribution: two people with the same BMI can have very different amounts of belly fat, which carries more risk.
- Age: older adults can lose muscle and gain fat with little change in BMI.
- Not for everyone: children and teenagers need age-specific BMI charts, and BMI isn't meaningful during pregnancy.
Waist-to-height ratio: a useful second check
Measure your waist at the level of your belly button, breathing out normally, and divide it by your height in the same units. A simple rule of thumb: keep your waist to less than half your height. For someone 165 cm tall, that means a waist under about 82 cm.
Indian guidelines also flag a waist of 90 cm or more in men and 80 cm or more in women as abdominal obesity. If you are above these numbers, a small calorie deficit, more daily walking and strength training are the best places to start — see how to lose belly fat.
Worked example: Priya and Rahul
Priya: 60 kg, 1.60 m → 60 ÷ (1.60 × 1.60) = 23.4. Healthy on the international scale, but in the overweight band on Indian cut-offs.
Rahul: 75 kg, 1.75 m → 75 ÷ (1.75 × 1.75) = 24.5. Also healthy internationally and overweight on Indian cut-offs — but Rahul lifts four days a week, so some of that weight is muscle. His waist measurement would tell him more than his BMI.
Neither needs to panic. Both are good candidates for keeping an eye on waist size and following a sensible plan from the calorie calculator.
How this calculator works
BMI = weight (kg) ÷ height (m)². If you enter pounds or feet and inches, we convert them first. The result is rounded to one decimal place and compared with the WHO international categories and the Indian/Asian cut-offs (23 for overweight, 25 for obesity).
This calculator is designed for adults aged 18 and over. It is not suitable for children, teenagers or during pregnancy.
Sources
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet, 2004.
- Misra A, et al. Consensus statement for diagnosis of obesity, abdominal obesity and the metabolic syndrome for Asian Indians. J Assoc Physicians India, 2009.
- World Health Organization. Obesity and overweight — fact sheet.
Frequently asked questions
Straight answers about this calculator. Educational only — not medical advice.
Indian guidelines consider 18.5–22.9 the healthy range for adults. A BMI of 23–24.9 is classed as overweight and 25 or more as obesity, lower than the international cut-offs of 25 and 30.
The formula and adult categories are the same for men and women. Women naturally carry more body fat at the same BMI, which is one reason BMI should be read alongside other measures.
Probably not, if your waist is less than half your height and you feel well. BMI can't tell muscle from fat. A waist measurement or body-fat estimate is more useful for you.
Internationally, a BMI of 30 or more. For Asian Indians, guidelines use 25 or more because health risks rise at lower BMIs in this population.
Losing body fat through a moderate calorie deficit, more daily movement and strength training will lower your BMI over time. Use the calorie calculator to find a realistic target.
Less so. Older adults often lose muscle, so BMI can look normal while body fat rises. Waist measurement and strength are useful extra checks.
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This calculator provides an estimate and isn't a substitute for individualised medical or dietary advice. Read our medical disclaimer and editorial policy.