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BMI Calculator
Calculate your Body Mass Index and see your weight category.
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Your BMI
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Category
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How to use the BMI Calculator
Choose imperial or metric, enter your height and weight, and your BMI and category appear instantly.
The BMI formula
BMI = weight (kg) ÷ height (m)2. In imperial units: 703 × weight (lb) ÷ height (in)2. Categories: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obesity.
What BMI doesn't measure
BMI is a screening tool, not a diagnosis. It can't distinguish muscle from fat, so athletes and very muscular people often land in "overweight" while being lean. For a fuller picture, pair your result with our body fat calculator (US Navy method) or ideal weight calculator.
Frequently Asked Questions
Body Mass Index = weight(kg) ÷ height(m)². It's a screening tool, not a diagnosis — muscle, bone density and distribution aren't captured.
Under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obesity.