BMI Calculator
Calculate your Body Mass Index with metric or imperial units. Get your BMI category (Underweight, Normal, Overweight, Obese) instantly. No signup required.
What is BMI Calculator?
Body Mass Index (BMI) is a numerical value calculated from height and weight, used as a screening tool to categorise weight relative to health risk. The formula is weight (kg) divided by height (m) squared. The World Health Organisation defines four categories: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (≥ 30). This calculator supports both metric (kg/cm) and imperial (lb/in) units.
BMI is a widely used population-level screening measure, but it has limitations as an individual health indicator. It doesn't account for muscle mass, bone density, age, sex, or fat distribution. A person with high muscle mass may have an elevated BMI without excess body fat, while someone with normal BMI may have an unfavourable fat-to-muscle ratio. Always consult a healthcare professional for a complete health assessment.
All calculations run locally in your browser. Your measurements are never sent to any server, stored, or logged. Switch between metric and imperial units at any time — the values convert automatically.
How to use
Frequently asked questions
The WHO considers 18.5–24.9 as the Normal range. Below 18.5 is Underweight, 25–29.9 is Overweight, and 30+ is Obese. For children and teens, age- and sex-specific charts are used instead.
No. Athletes with high muscle mass often have elevated BMIs that classify them as Overweight or Obese, even though their body fat percentage is healthy. BMI is a population-level tool, not an individual diagnosis.
Yes. All calculations run in your browser. No measurements are sent to any server.
BMI = weight (kg) / height (m)². For imperial: BMI = (weight in lbs × 703) / height in inches².