General and clinical
BMI calculator
Body mass index is weight divided by height squared, and it places a person in a weight band. This calculator shows both the WHO international bands and the lower Asian-Indian cut-offs, because they disagree and the Indian ones are the relevant pair here.
Enter the values
The result appears as you type.
Nothing is sent anywhere. The calculation runs entirely in your browser.
This calculator is provided for reference and education. It does not replace clinical assessment, examination, current guidelines, local protocol, or professional judgment. Verify every result before acting on it. Nirogix accepts no liability for clinical decisions made using this tool.
The formula
- BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = [weight (lb) ÷ height (in)²] × 703
Worked example
70 kg and 1.75 m → 70 ÷ (1.75)² = 70 ÷ 3.0625 = 22.9 kg/m²
When to use it
- Screening an adult population, or tracking one adult over time
- As one input to a risk conversation, alongside waist circumference
And when not to
- BMI does not distinguish muscle from fat, so it misclassifies athletes and the very muscular.
- It is not valid for children. Use a growth chart plotted against age and sex.
- It performs poorly in pregnancy, in the frail elderly, and after limb amputation.
- Body composition differs by ethnicity, which is exactly why the Asian-Indian cut-offs sit lower.
References
- Obesity: preventing and managing the global epidemic — WHO Technical Report Series 894, 2000
- Appropriate body-mass index for Asian populations — WHO expert consultation, The Lancet, 2004
- Consensus statement for diagnosis of obesity in Asian Indians — Journal of the Association of Physicians of India, 2009
Last reviewed 07/09/2026.
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These calculators are free and always will be. We also build Nirogix, a hospital management system for Indian clinics and hospitals. The same calculations are planned inside the consultation record, pre-filled from the chart.