BMI Calculator
Get your Body Mass Index with the category that actually fits you — switch between global WHO cut-offs and the stricter ICMR thresholds for Indians and South Asians — plus your healthy-weight range and a waist-based risk check.
Your measurements
Waist check — optional
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Your BMI on both standards
The same number can mean different things depending on which guideline applies to you.
How BMI is calculated
Body Mass Index is a quick screen for whether your weight is in a healthy range for your height. The formula is simply your weight divided by the square of your height:
Metric: BMI = weight (kg) ÷ height (m)²
Imperial: BMI = weight (lb) ÷ height (in)² × 703
This calculator converts imperial input to metric first, so you get the same answer whichever units you use. For example, someone 165 cm tall weighing 65 kg has a BMI of about 23.8.
WHO vs ICMR: why the standard matters
That 23.8 example is exactly why the choice of standard is so important. Under the global World Health Organization cut-offs it counts as a healthy weight. But under the Indian Council of Medical Research (ICMR) thresholds — developed because South Asians develop insulin resistance, type-2 diabetes and heart disease at lower BMI values — the same 23.8 is classed as overweight.
South Asians tend to carry a higher percentage of body fat, and more of it around the abdomen, at any given BMI. This is sometimes called being "metabolically obese, normal weight." Using generic cut-offs can therefore falsely reassure someone who is actually at raised risk, which is why this tool lets you switch standards and makes the difference explicit.
| Category | WHO (global) | ICMR (Indian / South Asian) |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Healthy weight | 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 |
Why waist circumference is worth adding
Because BMI uses only height and weight, it cannot separate fat from muscle, or see where fat sits. Abdominal (visceral) fat is the type most strongly tied to metabolic disease, and waist circumference captures it directly. For South Asians, a waist above 90 cm for men or 80 cm for women signals high-risk abdominal obesity — and can flag risk even when BMI looks fine. Measure horizontally at the level of your navel, on bare skin, without pulling the tape tight.
What BMI can and cannot tell you
BMI is a fast, well-validated screen, but it is only a starting point. It does not distinguish adipose tissue from muscle, so a fit, muscular person can register as "overweight" despite very low body fat — the so-called bodybuilder paradox. Frame size, age and sex all shift what a given number means, and for anyone under 18, BMI must be read against age-and-sex percentile charts instead of the adult bands above. Treat your result as one signal among several, alongside waist size, body-fat percentage and how you actually feel.
Using your result well
If your BMI sits above the healthy range for your chosen standard, the tool shows how much weight would bring you into it — but the route there matters more than the number. Sustainable change of around 0.5 kg per week, built on a balanced diet and regular movement, is far more effective and safer than crash dieting. If your BMI is low, or you are unsure what your result means for you, a doctor or dietitian can give you personalised guidance.
Frequently asked questions
What is a normal BMI for Indians and South Asians?
Under the ICMR guidelines, a healthy BMI is 18.5 to 22.9 — lower than the WHO's 18.5 to 24.9. From 23.0 to 24.9 is overweight, and 25.0 or above is obese. The thresholds are lower because South Asians carry more body fat, especially abdominal fat, and face higher diabetes and heart risk at a given BMI.
Is a BMI of 24 overweight in India?
By the ICMR / Asian standard, yes — 24 falls in the 23.0–24.9 overweight band, even though WHO classes it as normal. Switch the standard toggle above to see both, and add your waist measurement for a fuller picture.
How is BMI calculated?
It is your weight divided by the square of your height: kilograms ÷ metres² in metric, or pounds ÷ inches² × 703 in imperial. This tool converts automatically, so both give the same result.
Is BMI accurate for muscular people or athletes?
Not always — BMI can't tell muscle from fat, so muscular people may read as overweight at low body fat. Use the waist check here, and consider a body-fat measurement, for a clearer view.
Why does waist size matter alongside BMI?
Waist circumference reflects visceral fat, which drives metabolic risk. For South Asians, above 90 cm (men) or 80 cm (women) signals high-risk abdominal obesity, sometimes even when BMI looks acceptable.
Does BMI work the same for children?
No. Under-18s are assessed against age-and-sex percentile charts, not the fixed adult bands. This tool is for adults.