| BMI Range | Category |
|---|---|
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Body mass index, or BMI, approximates body fat by dividing a person’s weight by the square of their height, generating a dimensionless health indicator. Public-health agencies use BMI thresholds to flag underweight conditions, normal ranges, and escalating obesity classes linked to cardiovascular or metabolic risks. Although imperfect for muscular or elderly groups, BMI offers a fast, widely recognised snapshot of weight-related health status for most adults.
This calculator accepts weight in kilograms or pounds and height in centimetres, metres, or inches, instantly converting them to standard units through its reactive engine. The internal processor then divides the normalised weight by the squared height, classifies the result against medical thresholds, and plots it on an interactive gauge.
Use the calculator after an annual check-up to see whether dietary or activity changes shifted your BMI into safety or toward risk. Interpret the number cautiously; athletes, children, and older adults often require specialised evaluation. Discuss results with a healthcare provider before changing nutrition or exercise strategies. This calculator offers informational estimates, not medical advice.
BMI converts mass and height into a ratio (kg · m-2) expressing tissue mass per square metre. International bodies correlate threshold bands with morbidity and mortality risk, allowing non-clinical screening across large populations. Because height is squared, stature errors amplify more than weight errors, making accurate measurement essential.
| BMI Range | Category |
|---|---|
| < 16.5 | Severely Underweight |
| 16.5 – 18.4 | Underweight |
| 18.5 – 24.9 | Normal |
| 25 – 29.9 | Overweight |
| 30 – 34.9 | Obese I |
| 35 – 39.9 | Obese II |
| ≥ 40 | Obese III |
Each ascending category correlates with progressively higher probability of hypertension, Type 2 diabetes, and cardiovascular events. Normal range aligns with the lowest all-cause mortality in adult cohorts.
Example: 72 kg and 1.78 m → BMI = 72 ÷ 1.78² ≈ 22.7.
Result falls in the Normal band, suggesting balanced weight relative to height.
Concept validated by Keys et al. (1972) and refined through WHO Technical Report Series 894; critiques found in PLOS One and The Lancet.
Inputs are generic physical measures; under GDPR they constitute personal health data and require user consent when stored, which this tool avoids.
Follow these quick steps to produce an accurate reading.
No. All calculations occur locally; values vanish when you close the page.
Kilograms or pounds for weight, centimetres, metres, or inches for height; conversions run automatically.
Paediatric growth charts use age-specific centiles; this adult calculator is unsuitable for children.
Yes. Highly muscular individuals may register as overweight despite low body-fat percentages.
Most adults reassess annually unless under active weight-management plans requiring more frequent monitoring.