BMI calculator
Body mass index from height and weight, with the WHO adult category.
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This is a reference implementation of a published formula, provided for use by qualified healthcare professionals. It does not diagnose, does not account for the individual circumstances of any patient, and is not a recommendation for treatment. Confirm every result against your own institutional guidance before acting on it. Clinical judgement always takes precedence over a calculator.
About this calculation
Body mass index relates weight to height. It is a population screening measure, not a measure of body composition, and the adult categories below come from the World Health Organization classification.
Formula
BMI = weight (kg) ÷ height (m)²
- Source
- World Health Organization — Body mass index classification (1995)
- Methodology version
- 1.0.0
- Last reviewed
- 2026-10-28
What this does not account for
- BMI does not distinguish muscle from fat, so it overestimates adiposity in muscular people and underestimates it where muscle mass is low.
- The adult categories do not apply to children or adolescents, who are assessed on age-and-sex-specific percentiles.
- The thresholds were derived in predominantly European populations; several bodies use lower cut-points for people of South and East Asian ancestry.
- BMI says nothing about where fat is distributed, which is what most of the cardiometabolic risk tracks.