Health and clinical reference
BMI calculator with WHO adult categories
Body mass index for adults in metric or US units, with the World Health Organization category and the weight range for a BMI of 18.5 to 24.9.
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For information only. This is a reference calculation, not medical advice or a diagnosis, and it must not be used to choose or adjust medicine doses. Discuss any result or health decision with a qualified clinician.
Result
Method and limits
Body mass index divides weight by the square of height. The World Health Organization classifies adult BMI as underweight below 18.5, normal weight 18.5–24.9, pre-obesity 25.0–29.9, obesity class I 30.0–34.9, class II 35.0–39.9 and class III 40 and above.
BMI = weight (kg) / height (m)²Assumptions and limits
- For adults aged 18 and over. Children and teenagers use age- and sex-specific BMI percentiles instead.
- BMI does not distinguish muscle from fat or show where fat is carried; it is not reliable in pregnancy, and some populations use lower cut-offs.
Worked example
70 kg at 175 cm gives a BMI of 22.9 kg/m², in the normal-weight range; at that height, BMI 18.5–24.9 corresponds to 56.7–76.3 kg.
References
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