body mass index

American  

[bod-ee mas in-deks] / ˈbɒd i ˌmæs ˌɪn dɛks /

noun

1. an index for assessing overweight and underweight, obtained by dividing body weight in kilograms by height in meters squared: a measure of 25 or more is considered overweight.

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body mass index British  

noun

1.  BMI.  an index used to indicate whether a person is over- or underweight. It is obtained by dividing a person's weight in kilograms by the square of their height in metres. An index of 20–25 is normal

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body mass index Scientific  

/ bŏd′ē /

1. A measurement of the relative percentages of fat and muscle mass in the human body, in which weight in kilograms is divided by height in meters squared. The result is used as an index of obesity.

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Etymology

Origin of body mass index

First recorded in 1955–60

Example Sentences

It also gave the president the exact height and weight ratio to keep him right under an “obese” body mass index, a designation so convenient as to be laughable.

From Salon • Jun. 1, 2026

Conditions related to heart and metabolic health, including hypertension and elevated body mass index, showed steeper negative associations with cognition among women.

From Science Daily • May 20, 2026

About 48% of people covered by Medicare are obese, while 38% of Americans on Medicaid and the Children’s Health Insurance Program have a body mass index of 30 or higher.

From MarketWatch • Apr. 21, 2026

The standard way of categorising people's weight is by calculating their body mass index, or BMI.

From BBC • Feb. 24, 2026

The asthma was under control, but the doctor alerted me to something else—Malia’s body mass index, a measure of health that factors together height, weight, and age, was beginning to creep up.

From "Becoming" by Michelle Obama