Clinical Calculators

BMI (Body Mass Index)

Calculates body mass index from height and weight and classifies it with the adult weight-status categories used by the WHO and the CDC

2 items left

130 to 200
cm
30 to 150
kg

Formula

  • BMI (kg/m²) = weight (kg) ÷ height (m) squared
  • Categories for adults: under 18.5 underweight; 18.5 to under 25 healthy weight; 25 to under 30 overweight; 30 to under 35 class 1 obesity; 35 to under 40 class 2 obesity; 40 or more class 3 obesity (severe obesity)

Cautions

  • These categories are for adults. For children and adolescents the WHO uses age-specific growth references (BMI-for-age in standard deviations; weight-for-height under 5 years), so do not use these categories for them.
  • BMI does not measure body fat directly. In a muscular person, or a person whose weight is raised by fluid, a BMI of 25 or more does not necessarily mean excess fat.
  • A BMI in the overweight or obesity range does not by itself show that weight loss is needed or that disease is present. Interpret it together with the rest of the clinical picture.
  • The category is chosen from the value as displayed, to one decimal place. A calculated 24.96 is displayed as 25.0, so it falls in the overweight category.

References

  1. World Health Organization. Obesity and overweight (fact sheet). Geneva: WHO. (Definitions of overweight and obesity) https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight[Guideline]
  2. World Health Organization. Global Health Observatory: Body mass index (BMI) indicators. Geneva: WHO. (Body mass index indicators) https://www.who.int/data/gho/data/themes/topics/topic-details/GHO/body-mass-index[Guideline]
  3. Centers for Disease Control and Prevention. BMI categories for adults 20 and older (Adult BMI Categories). Atlanta: CDC. (BMI categories for adults 20 and older (the weight-status table)) https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html[Guideline]
  4. World Health Organization. Obesity: preventing and managing the global epidemic. Report of a WHO Consultation. WHO Technical Report Series 894. Geneva: WHO; 2000. (original not seen)[Guideline]
  5. Keys A, Fidanza F, Karvonen MJ, Kimura N, Taylor HL. Indices of relative weight and obesity. J Chronic Dis. 1972;25(6):329-343. (original not seen) PMID: 4650929, DOI: 10.1016/0021-9681(72)90027-6[Original article]

Checked on: 2026-11-07

Disclaimer

This calculation is intended to support the judgment of healthcare professionals. Results are for reference only; decisions about diagnosis and treatment must be made by the responsible healthcare professional. The values you enter never leave your device.