Calculate your Body Mass Index from height and weight in metric or imperial units, and see which BMI category your result falls into.
Your BMI
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How It Works
Body Mass Index is weight in kilograms divided by height in meters squared: BMI = kg / m². It gives a single number that estimates body fat relative to height for most adults.
For imperial inputs, weight in pounds is divided by 2.205 to get kilograms and height in inches is multiplied by 0.0254 to get meters, then the same formula is applied.
Standard adult categories are: underweight below 18.5, normal weight 18.5–24.9, overweight 25–29.9, and obese 30 or above. These ranges are the same for men and women but are not a direct measure of body fat or health.
Worked example: a person who is 5 ft 9 in (69 in, or 1.7526 m) and weighs 160 lb (72.56 kg) has BMI = 72.56 / (1.7526)² ≈ 23.6, which falls in the normal weight range.
Frequently Asked Questions
Is BMI accurate for athletes or very muscular people?
BMI does not distinguish muscle from fat, so very muscular people can register as overweight or obese despite low body fat. It is a screening tool, not a diagnosis.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range. Values outside that range may warrant a conversation with a healthcare provider.
Should I use metric or imperial units?
Either works. The calculator converts imperial height and weight to metric before applying the standard BMI formula, so the result is identical for the same measurements.
Does BMI mean the same thing for men and women?
The category cutoffs are the same, but at the same BMI women tend to have slightly more body fat than men. BMI is a population-level screen, so individual body composition can vary.
Is BMI suitable for children or teens?
Not directly. Children and teens use BMI-for-age percentile charts rather than the fixed adult categories, so a 12-year-old with a BMI of 22 may be in a very different percentile than an adult with the same value.
What are the limitations of BMI?
BMI ignores body composition, fat distribution, age, and sex differences. Two people with the same BMI can have very different health risk profiles, so it should be paired with other measures like waist circumference for a fuller picture.