BMI Calculator
What's your BMI?
Body Mass Index in kg/m². WHO categorises your number, and we also flag the South-Asian threshold (≥ 23 = overweight) when it applies — Indians carry more visceral fat at lower BMIs than other populations.
BMI is a quick screen, not a verdict. It can't tell muscle from fat — for athletes use the body-fat calculator instead.
Enter your weight and height, then tap Calculate BMI to see your BMI and which WHO category it falls in. We also surface the South Asian threshold in case it applies to you.
BMI categories — WHO and Indian thresholds
BMI gives a single number that places your weight relative to your height, but the meaning of that number depends on which reference standard you use. The WHO chart is the global default. Indian-population guidelines (ICMR / Lancet / WHO South-East Asia) shift the cut-offs five points lower because South Asians develop metabolic disease at lower BMIs.
| BMI (kg/m²) | WHO category | Indian / South-Asian |
|---|---|---|
| Below 18.5 | Underweight | Underweight |
| 18.5 – 22.9 | Healthy | Healthy |
| 23.0 – 24.9 | Healthy | Overweight (action zone) |
| 25.0 – 29.9 | Overweight | Obese, class I |
| 30.0 – 34.9 | Obese, class I | Obese, class II |
| 35 and above | Obese, class II / III | Obese, class III |
So which threshold should I use?
How to calculate BMI manually
BMI is one of the simplest health metrics in medicine — it's just a ratio of your weight to your height squared.
Formula
BMI = weight (kg) ÷ height (m)2
For pounds and feet: multiply pounds by 0.453592 to get kg, multiply feet by 0.3048 to get metres, then plug in.
Worked example. A 1.70 m, 70 kg adult: 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2. On the WHO chart, that's comfortably in the healthy band. On the South-Asian chart it's already "overweight", and this person would be smart to start tracking waist circumference and fasting glucose on top of weight.
Why BMI is not the whole picture
BMI's biggest virtue is also its biggest flaw: it's just weight ÷ height. It cannot see the difference between muscle and fat, where fat is stored, bone density, or hydration. Use it as a starting signal, not a diagnosis.
BMI under-reads risk in these groups
- Lean, muscular lifters — high BMI from muscle, not fat.
- Older adults — muscle loss can keep BMI "normal" while body-fat percentage climbs.
- South Asians — more visceral fat at the same BMI than European populations, hence the 23 / 25 cut-offs above.
- Pregnancy — BMI during pregnancy is not meaningful; use pre-pregnancy BMI only.
- Children and teenagers — use paediatric percentile charts, not the adult 18.5 / 25 / 30 lines.
For body composition specifically, our body-fat calculator uses the US Navy method (waist + neck + height + hips for women), which is far less misleading for muscular folks.
What your BMI says about disease risk
Population studies have linked higher BMI to elevated risk of type 2 diabetes, hypertension, fatty liver, sleep apnoea and several cancers. The lift in risk isn't linear — most metabolic harm shows up above the "overweight" threshold, and waist-to-height ratio tends to predict outcomes more reliably than BMI alone.
The practical takeaway: if your BMI is in the action zone for your population reference, the next thing to measure is your waist circumference. Waist over 90 cm (men) or 80 cm (women) for South Asians strongly suggests visceral fat and is worth a conversation with a GP — even if BMI alone looks unremarkable.
BMI calculator — frequently asked questions
Quick answers to the things people search for after running their numbers.
What is a healthy BMI for an Indian adult?
WHO's standard healthy band is 18.5–24.9. The Indian Council of Medical Research (ICMR) and most public-health guidelines for South Asians use 18.5–22.9 instead, because Indians develop diabetes and heart disease at lower BMIs than other populations. So a BMI of 23–24.9 looks 'normal' on the WHO chart but is already a health flag in the Indian context.
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². If your weight is in pounds, multiply by 0.453592 to get kilograms; if your height is in feet, multiply by 0.3048 to get metres. Example: 70 kg, 1.70 m → 70 ÷ (1.70 × 1.70) = 24.2.
Is BMI accurate for athletes or muscular people?
No. BMI doesn't distinguish between fat and muscle. A lean, muscular lifter can land in the 'overweight' or even 'obese' band on BMI alone, while the same number could mean over-fat in someone sedentary. For body composition, use a body-fat calculator or DEXA scan instead.
What is the BMI range for women vs men?
BMI thresholds are the same for adult men and women — there's no separate male and female chart. Body composition differs (women have higher essential fat), but the BMI cut-offs WHO publishes apply uniformly. Where men and women diverge is in body-fat percentage interpretation, not BMI.
Why does the South Asian threshold start at 23?
Lancet, ICMR and WHO regional studies consistently show that people of South Asian ancestry carry more visceral (organ) fat at any given BMI compared to European populations. That visceral fat drives insulin resistance, fatty liver and cardiovascular risk much earlier. India-specific guidelines therefore use BMI ≥ 23 as 'overweight' and ≥ 25 as 'obese' — five points lower than the WHO standard.
Does BMI work during pregnancy?
No — pre-pregnancy BMI is meaningful, but BMI during pregnancy isn't. Healthy gestational weight gain depends on starting BMI, single vs. multiple pregnancy, and other factors your obstetrician tracks. Don't try to 'fix' a high BMI mid-pregnancy.
Is it OK to use BMI for kids and teenagers?
Adult BMI cut-offs (18.5 / 25 / 30) are not appropriate for under-18s. Paediatric BMI uses age- and sex-specific percentile charts (CDC growth charts in the US, IAP charts in India). This calculator is intended for adults 18 and over.
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