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The History of BMI

Written by the HowToCalculateBMI.org team Updated 1 min read

Checked against 8 cited sources

BMI was invented by Adolphe Quetelet, a Belgian mathematician and astronomer, in the 1830s, as a way to describe the "average man" in population statistics. It was known as the Quetelet index until 1972, when the American physiologist Ancel Keys named it the body mass index. It became the standard way to classify weight in the 1990s.

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Timeline

Year Event
1830s Adolphe Quetelet observes that adult weight rises roughly with the square of height, and uses weight ÷ height² in his population statistics1
1972 Ancel Keys and colleagues compare weight-for-height formulas against body fat and find weight ÷ height² works best; he names it body mass index1
1980s BMI spreads through medicine and research
1995–2000 The World Health Organization sets the categories still used today: 25 for overweight and 30 for obesity23
1998 The US National Institutes of Health adopts 25 as the overweight cutoff, replacing higher sex-specific cutoffs4
2000 The CDC publishes BMI-for-age growth charts for children and teens aged 2 to 195
2004 A WHO expert consultation proposes lower action points, 23 and 27.5, for Asian populations6
2013 Oxford mathematician Nick Trefethen proposes a "new BMI" using height to the power of 2.57
2022 The CDC releases extended BMI-for-age charts for children with very high BMIs8

Quetelet's original idea

Quetelet wasn't studying health or obesity. He was a pioneer of statistics who wanted to describe the typical measurements of a population. He noticed that weight in grown adults increases roughly with the square of height, not in direct proportion, and that dividing weight by height squared gave a number that varied far less between people.1

Why Keys chose BMI

In 1972, Ancel Keys tested several weight-for-height formulas on thousands of men in different countries, comparing each with body fat measured from skinfolds and body density.1 Weight ÷ height² matched body fat best and was simplest to calculate. He was clear it was best for comparing populations, not for judging individuals, a caution that still applies.1 What BMI can and can't tell you.

Frequently asked questions

Who invented BMI?

Adolphe Quetelet, in the 1830s. Ancel Keys gave it the name "body mass index" in 1972.1

Was BMI designed to measure health?

No. Quetelet created it for population statistics. It was adopted for health screening much later because it tracks body fat reasonably well for most adults.3

Sources

  1. Keys et al. (1972), Journal of Chronic Diseases ↩ ↩ ↩ ↩ ↩ ↩

  2. WHO Technical Report Series 854 (1995), Physical status: the use and interpretation of anthropometry ↩

  3. WHO Technical Report Series 894 (2000), Obesity: preventing and managing the global epidemic ↩ ↩

  4. NIH/NHLBI (1998), Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults ↩

  5. Kuczmarski et al. (2002), CDC growth charts methods ↩

  6. WHO expert consultation (2004), The Lancet ↩

  7. Trefethen, University of Oxford (2013) ↩

  8. CDC: extended BMI-for-age growth charts (2022) ↩

Further reading

Written by

The HowToCalculateBMI.org team

We explain BMI in plain language, check every worked example with automated tests, and keep each page up to date with current guidelines.

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Kept up to dateLast updated October 9, 2026

This page is for education and is not medical advice. Talk with a healthcare professional about your weight and health.

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