How to Calculate BMI: Formula, Chart & Meaning

Body Mass Index (BMI) is a quick screen for healthy weight.

BMI formula

BMI = weight (kg) / height (m)². In imperial: BMI = 703 × weight(lb) / height(in)².

Example

A person 70 kg and 1.75 m tall: 70 / (1.75×1.75) = 22.9 — a healthy BMI.

BMI categories

Under 18.5 = underweight, 18.5–24.9 = normal, 25–29.9 = overweight, 30+ = obese.

Limitations

BMI does not distinguish muscle from fat, so athletes may read high.