Check your Body Mass Index and weight category in metric or imperial units.
Health figures are processed locally and never stored.
Understanding your result
BMI is a population-level screening tool, not a diagnosis. It does not distinguish muscle from fat and may misclassify very muscular or older individuals. Use it as a general guide alongside professional advice.
Formula and method
Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = 703 × weight (lb) ÷ height (in)². Standard adult categories: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese.
Worked example
A person 175 cm tall weighing 70 kg has a BMI of 70 ÷ (1.75 × 1.75) = 22.9, which falls in the normal range.
How to use this tool
- Choose metric or imperial units.
- Enter your height and weight.
- Press Calculate to see your BMI and category.
Common mistakes to avoid
- Entering height in centimetres while the metric formula expects metres internally (the tool converts for you).
- Treating BMI as a body-fat percentage — it is not.
About the BMI Calculator
Body Mass Index (BMI) is a simple screening number that relates weight to height. This calculator returns your BMI and the standard weight category in either metric or imperial units.
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Frequently asked questions
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so very muscular people can show a high BMI while being healthy.
Does this work for children?
These categories are for adults. Children use age- and sex-specific percentile charts instead.