BMI Calculator
Enter weight and height in metric or US units. BMI is mass divided by height squared, then placed in a WHO adult category.
How it works
BMI = kg / m². Imperial entries are converted, which is the same as 703 × lb / in². Categories used here are the WHO adult cut-offs: underweight < 18.5, healthy 18.5–24.9, overweight 25–29.9, obesity ≥ 30.
BMI does not know muscle, bone, pregnancy or ethnicity. It is a screening number, not a health assessment.
Formula
BMI = kg / m² BMI = 703 × lb / in²
Worked examples
A metric example
70 kg, 175 cm → BMI ≈ 22.9 (healthy weight)
Useful notes
- WHO cut-offs are for adults. They are not applied to children on this page.
- Not medical advice.
FAQ
- How do I calculate BMI?
Divide weight in kilograms by height in metres squared.
- Is BMI the same as body fat?
No. BMI uses only height and weight. A tape or DEXA estimate of fat is a different measurement.
- Is this a diagnosis?
No. It is a published index with known limits, not a clinical opinion.
Related tools
Healthy Weight
Show the adult weight range that corresponds to WHO BMI 18.5–24.9 for a given height.
Ideal Weight
Estimate Devine (1974) ideal body weight from height and the male or female equation.
Body Fat Calculator
Estimate body-fat percentage from the U.S. Navy circumference (tape) method.
BMR Calculator
Estimate basal metabolic rate with the Mifflin-St Jeor equation from sex, age, height and weight.
Lean Body Mass
Estimate lean body mass with the Boer (1984) equations from sex, height and weight.
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