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How to use the bmi calculator
- 1Enter your height — centimetres, or feet and inches in separate fields.
- 2Enter your weight in kilograms.
- 3Choose the cutoffs: the Asian-population thresholds (the default, and the ones Indian guidelines follow) or the WHO standard.
- 4Read your BMI, its category, and the healthy weight range for your height.
What BMI measures, and the cutoff question
BMI is weight in kilograms divided by height in metres squared — a screening ratio invented to compare populations, pressed into service for individuals because it is free and instant. The standard WHO bands call under 18.5 underweight, 18.5–25 healthy, 25–30 overweight and 30+ obese.
For South Asians the standard bands understate risk: studies consistently show cardiovascular and diabetes risk rising at lower BMIs in Indian populations, so Indian guidelines and the WHO's own Asian-population recommendations draw the lines at 23 (overweight) and 27.5 (obese) instead. This calculator defaults to those cutoffs — a BMI of 24 reads 'healthy' on a Western calculator and 'overweight' under the guidelines that actually apply here, and that difference is the point.
The healthy-range figure the tool shows — 18.5 to the overweight cutoff, converted into kilograms for your height — is usually more actionable than the index: it turns 'BMI 26.1' into 'about 4 kg above the range', which is a plan rather than a label.
Where BMI misleads, honestly listed
BMI cannot tell muscle from fat: a fit, muscular person can read overweight while carrying less fat than a slim-limbed person with abdominal weight who reads normal. The second pattern — 'normal-weight central obesity' — is common in South Asia and is exactly what BMI misses; waist circumference (broadly, risk rises past ~90 cm for men and ~80 cm for women) catches it and takes one tape measure.
Age and life stage move the picture too: for older adults, slightly higher BMIs associate with better outcomes, and the index is not designed for pregnancy or for children (who use age-specific percentile charts, not these bands). For anyone under 18, a paediatric chart is the right tool, not this page.
So read the output as a screening flag, not a verdict: one number, best interpreted alongside waist, blood pressure, sugar and lipids — the panel a routine check-up covers. A BMI in the flagged range is a reason for that check-up, not a diagnosis from a web page.
Moving the number, without folklore
The uncomfortable, well-replicated truth: weight is lost in the kitchen far more than the gym. A sustainable 300–500 kcal daily deficit — smaller portions, fewer liquid calories, protein at every meal — moves weight at the safe 0.25–0.5 kg per week; exercise's biggest contributions are keeping it off, preserving muscle, and improving every marker BMI cannot see.
Crash outcomes are baked into the arithmetic: a deficit aggressive enough to drop 3 kg in a fortnight is mostly water and muscle, and reverses the same fortnight it stops. The boring compounding of a modest deficit — the SIP of body weight, if you like — is what actually shifts the range on this calculator over months.
If the number lands in the underweight band, the same honesty applies in reverse: unintentional weight loss or a persistently low BMI deserves a doctor's look at causes before it deserves a calorie surplus. Screening numbers exist to route people to humans, and this one is no exception.
Frequently asked questions
What is a healthy BMI in India?
Under the Asian-population cutoffs Indian guidelines follow: 18.5 to 23. From 23 to 27.5 counts overweight and beyond 27.5 obese — lower lines than the WHO standard, reflecting risk that rises earlier in South Asian populations.
Why does this calculator default to Asian cutoffs?
Because for South Asian users the standard bands understate metabolic risk — diabetes and heart disease appear at lower BMIs. The toggle shows the WHO standard whenever you need the international reading.
Is BMI accurate for muscular people?
No — it counts muscle as if it were fat, so athletic builds read heavier than they are. Pair the number with waist circumference; a muscular 'overweight' reading with a normal waist is usually the calculator's error, not yours.
What weight should I be for my height?
The tool computes it: 18.5 × height² to the overweight cutoff × height². At 170 cm under Asian cutoffs, roughly 53 to 66 kg — a range, because healthy is a band, not a point.
Does BMI apply to children or during pregnancy?
No — children use age-and-sex percentile charts and pregnancy has its own weight-gain guidance. This calculator is for non-pregnant adults; for both special cases, a clinician's charts are the right tool.
Is my height and weight uploaded?
No — one division in your browser. Health numbers are personal, and nothing you enter leaves the page.