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BMI Calculator

Work out your body mass index, see your WHO, Asian and Indian guideline category and find the healthy weight range for your height.

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BMI Calculator Nothing is stored or sent

For general information only, not medical advice. Results are estimates and do not replace a check-up with a doctor or other qualified health professional.

What your result means

Your BMI places you in a weight category, and the calculator shows it on three scales, one row each. The WHO scale is used worldwide. The Asian scale uses lower cut-offs because people of Asian origin, including Indians, face higher health risks at a lower BMI. The Indian guideline category follows the 2009 Indian consensus statement, which many Indian doctors use and which is the strictest of the three.

BMI (kg/m²) WHO category Asian category Indian guideline category (2009)
Below 18.5 Underweight Underweight Underweight
18.5 to 22.9 Healthy weight Healthy weight Normal
23.0 to 24.9 Healthy weight Overweight Overweight
25.0 to 27.4 Overweight Overweight Obese
27.5 to 29.9 Overweight Obese Obese
30.0 to 34.9 Obese class I Obese Obese
35.0 to 39.9 Obese class II Obese Obese
40.0 and above Obese class III Obese Obese

The Asian column follows the thresholds the NHS (opens in new tab) uses for people of South Asian, Chinese and other Asian backgrounds: 23 to 27.4 is overweight and 27.5 or more is obese. The Indian column follows the 2009 consensus statement for Asian Indians (opens in new tab), which counts 25 or more as obese.

So if you are Indian, a BMI of 24 is “healthy” on the WHO scale but overweight on both the Asian and Indian scales. A BMI of 26 shows as overweight on the WHO and Asian rows, but obese on the Indian guideline row, which is how an Indian doctor following that guideline would read it.

How BMI is calculated

BMI is your weight divided by the square of your height. Weight is in kilograms and height is in metres.

BMI = weight (kg) ÷ height (m)²

  • Weight (kg): your body weight in kilograms.
  • Height (m): your height in metres. 170 cm is 1.70 m.
  • Height (m)²: height multiplied by itself, so 1.70 × 1.70 = 2.89.

If you use pounds and inches, the imperial version is BMI = 703 × weight (lb) ÷ height (in)². The calculator converts imperial inputs to metric for you, so both give the same answer. The result is shown to one decimal place.

The healthy weight range for your height works the other way round. The calculator multiplies your height in metres squared by 18.5 for the lower limit, and by 24.9 (WHO) or 22.9 (Asian) for the upper limit.

How to use the BMI calculator

  1. Choose Metric (cm and kg) or Imperial (ft, in and lb).
  2. Enter your height without shoes.
  3. Enter your weight, ideally measured in the morning in light clothing.
  4. Read your BMI, your WHO, Asian and Indian guideline categories, and the healthy weight range for your height. The colour scale shows where you sit. Results update as you type.

Worked example

Ravi is 170 cm tall (about 5 ft 7 in) and weighs 70 kg (about 154 lb).

  1. Height in metres: 170 ÷ 100 = 1.70 m.
  2. Height squared: 1.70 × 1.70 = 2.89.
  3. BMI: 70 ÷ 2.89 = 24.22, shown as 24.2.

The calculator shows 24.2 as a healthy weight on the WHO row, and overweight on both the Asian and Indian guideline rows, because it is above 22.9.

His healthy weight range is 18.5 × 2.89 = 53.5 kg up to 24.9 × 2.89 = 72.0 kg on the WHO scale. On the Asian scale the upper limit is 22.9 × 2.89 = 66.2 kg. To move into the Asian healthy range, Ravi would need to lose about 4 kg.

BMI for Indians and South Asians

In 2004, a WHO expert consultation (opens in new tab) found that the share of Asian people at high risk of type 2 diabetes and heart disease is substantial below the usual overweight cut-off of 25. The BMI at which risk starts to rise ranged from 22 to 25 across Asian groups. WHO kept the global cut-offs but added public health action points at 23, 27.5, 32.5 and 37.5. The UK’s NHS uses 23 and 27.5 for Asian backgrounds, which is the Asian scale this calculator shows.

India went a step further. The 2009 consensus statement (opens in new tab) by Indian experts set overweight at a BMI of 23 to 24.9 and obesity at 25 or more for Asian Indians. It also defined abdominal obesity as a waist of 90 cm or more in men and 80 cm or more in women. The authors estimated these limits would label an extra 10% to 15% of Indians as overweight or obese.

The 2025 revised Indian definition of obesity

In January 2025, an Indian expert group led by Dr Anoop Misra, with doctors from AIIMS New Delhi, published a revised definition of obesity for Asian Indians (opens in new tab). It moves away from BMI alone:

  • Stage 1 obesity: BMI above 23, with no effect yet on daily activities or organ health.
  • Stage 2 obesity: BMI above 23 plus a high waist (90 cm or more in men, 80 cm or more in women) or a waist-to-height ratio above 0.5, plus either symptoms that limit daily life (such as breathlessness or joint pain) or a related disease such as type 2 diabetes, high blood pressure or fatty liver.

The same paper still grades BMI: 18.5 to 22.99 normal, 23 to 24.9 grade I, 25 to 27.5 grade II, 27.6 to 32.4 grade III and 32.5 or more grade IV. Under the newest Indian guidance, a BMI above 23 is your cue to measure your waist and check in with a doctor.

Why fat around the waist matters

Many Indians carry extra fat around the belly even at a normal BMI. This “central” fat is closely linked to diabetes and heart disease. So check your waist as well as your BMI. A simple rule from the NHS (opens in new tab): keep your waist to less than half your height. For a 170 cm person, that means a waist under 85 cm. Our body fat calculator uses waist and neck measurements to estimate body fat.

What to do next

If your BMI is above the healthy range, a small, steady calorie deficit works better than crash diets. The calorie calculator shows how much to eat to lose about 0.5 kg a week. The BMR calculator shows how many calories your body burns at rest. If your BMI is below 18.5, talk to a doctor, as being underweight can point to poor nutrition or an illness.

Even a modest change helps. The 2013 AHA/ACC/TOS obesity guideline (opens in new tab) found that a sustained loss of just 3% to 5% of body weight brings clinically meaningful drops in blood sugar and triglycerides, and a lower risk of type 2 diabetes. For a 70 kg person, that is 2 to 3.5 kg.

Limitations

BMI is a quick screening tool. It does not measure body fat directly and it cannot tell you about your health on its own.

  • Muscle: athletes and people with a lot of muscle can have a high BMI without excess fat.
  • Older adults: people tend to lose muscle with age, so BMI can look normal while body fat is high.
  • Pregnancy: BMI does not apply during pregnancy or breastfeeding.
  • Children and teens: anyone under 18 needs BMI-for-age charts, not adult cut-offs.
  • Fat location: BMI does not show where fat sits. Belly fat carries more risk than fat on the hips.
  • Ethnic background: the WHO cut-offs understate risk for South Asians, which is why the Asian and Indian scales exist.
  • Short-term changes: water, salt and a large meal can shift your weight by a kilo or more in a day. Weigh at the same time of day to track trends.

See a doctor if your BMI is below 18.5 or in the obese range, if you lose or gain weight without trying, or if you have high blood pressure, high blood sugar or a family history of diabetes or heart disease.

Key facts

FAQ

BMI Calculator FAQs

What is a healthy BMI for Indians?

A healthy BMI for Indian adults is 18.5 to 22.9. That is lower than the WHO range of 18.5 to 24.9, because Indians face a higher risk of type 2 diabetes and heart disease at a lower BMI. Indian guidelines call 23 to 24.9 overweight and 25 or more obese. Use the calculator to see the healthy weight range in kg for your height.

My BMI is 24. Am I overweight?

Yes, if you are Indian or South Asian, a BMI of 24 counts as overweight. On the WHO scale it is still healthy, but the Asian scale, the NHS and the Indian consensus guideline all put 23 to 24.9 in the overweight band. Check your waist too: 90 cm or more for men or 80 cm or more for women raises your risk further.

Is BMI accurate for athletes or muscular people?

No, BMI is often misleading for athletes and very muscular people. Muscle is dense and heavy, so a fit person can have a BMI in the overweight or even obese range with little body fat. BMI only uses height and weight. For muscular people, waist size or a body fat estimate gives a much better picture of health.

Why are BMI ranges lower for Indians and Asians?

BMI ranges are lower for Indians and Asians because they tend to carry more body fat, especially around the belly, at the same BMI. A 2004 WHO expert consultation found Asian groups develop diabetes and heart disease at lower BMI levels and suggested action points at 23 and 27.5. India’s 2009 guideline sets obesity at 25, and a 2025 revision at above 23.

Is BMI different for men and women?

No, adult BMI uses the same formula and the same cut-offs for men and women. However, at the same BMI, women usually have more body fat than men, and men are more likely to carry fat around the belly. That is why waist size and body fat percentage add useful detail to a BMI result, and why Indian waist limits differ by sex.

Can children use this BMI calculator?

No, this calculator is for adults aged 18 and over. Children and teens are still growing, so their BMI must be compared with BMI-for-age charts for their age and sex. In India, paediatricians use the Indian Academy of Pediatrics 2015 charts, which flag overweight and obesity at the child equivalent of an adult BMI of 23 and 27.

What BMI is considered obese?

On the WHO scale, a BMI of 30 or more is obese, split into class I (30 to 34.9), class II (35 to 39.9) and class III (40 or more). For Asian backgrounds, the NHS uses 27.5. India’s 2009 guideline defines obesity in Asian Indians as a BMI of 25 or more, and the 2025 revised Indian definition starts at a BMI above 23.

What is a better measure than BMI?

Waist circumference, waist-to-height ratio and body fat percentage add detail that BMI misses. A waist under half your height is a good target. Indian guidelines flag a waist of 90 cm or more in men and 80 cm or more in women. You can estimate body fat with our body fat calculator. Using BMI with waist size works best.