BMI Calculator

Body mass index from height and weight.

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Weight (kg)Height (cm)–

BMI is a rough screening measure for adults, not a diagnosis: it does not distinguish muscle from fat and is not meant for children, pregnant women or athletes. For health questions, talk to a doctor.

How to use this calculator

1 Enter your weight and height; the BMI and its WHO category appear immediately.
2 Switch to imperial to use pounds, feet and inches instead of kilograms and centimeters.
3 The formula is weight in kilograms divided by height in meters squared: 70 kg at 1.75 m gives 70 ÷ 1.75² = 22.9.
4 Read the result as a rough range, not a verdict; the note under the result explains its limits.

Frequently asked questions

What are the BMI categories?: For adults, the WHO ranges are: below 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, 30 and above obesity.
Is BMI accurate for everyone?: No. BMI ignores body composition: a muscular athlete can score 'overweight' while carrying little fat, and the ranges are not designed for children, pregnant women or the very elderly.
How is BMI calculated in imperial units?: Weight in pounds divided by height in inches squared, multiplied by 703. 154 lb at 5 ft 9 in gives 154 ÷ 69² × 703 = 22.7.
Does age or sex change the calculation?: The adult formula is the same for everyone; only the interpretation differs. For children and teens, doctors use age- and sex-specific percentile charts instead of the adult ranges.

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