⚖️ BMI Calculator
Calculate your Body Mass Index and see what it means for your healthy weight range.
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BMI — useful tool or outdated number?
Body Mass Index was invented in the 1830s by Adolphe Quetelet, a Belgian mathematician. He designed it to study population statistics — not to assess individual health. The formula (weight in kilograms divided by height in metres squared) was never intended to be used as a medical tool for individuals.
BMI became widely used in medicine from the 1970s onwards primarily because it's easy to calculate. Its limitations are well-documented but often glossed over:
- Muscle vs fat: BMI can't tell the difference. A heavily muscled AFL player or Olympic rower can register as 'overweight' despite having very low body fat.
- Ethnicity: Research suggests the risk thresholds may be too high for South Asian and East Asian populations, and potentially too low for some Indigenous Australians. The WHO has different threshold recommendations for some populations.
- Age and sex: The same BMI means different things at 25 versus 65. Older adults with a BMI in the 'normal' range may actually have insufficient muscle mass.
- Fat distribution: Where fat is stored matters more than total fat. Abdominal (visceral) fat carries more health risk than fat stored around the hips and thighs. Waist circumference is often a better predictor of metabolic risk.
🦘 Fun fact: Australia's average BMI has been rising steadily — about two-thirds of Australian adults are now classified as overweight or obese by BMI. But some researchers argue the better story is the rise in sedentary behaviour and ultra-processed food consumption, which BMI alone doesn't capture.