About this BMI calculator
The BMI calculator estimates Body Mass Index, a screening number used worldwide to classify weight relative to height. It is quick, free, and useful for tracking general health trends — though it does not measure body fat directly and is not a medical diagnosis.
CalCulator supports both metric (kg/cm) and imperial (lb/in) inputs and shows the World Health Organization adult categories.
How to use
- Select metric or imperial units.
- Enter your weight and height.
- Read your BMI and category (underweight, normal, overweight, or obese).
Formula
Categories (WHO, adults): Underweight < 18.5 · Normal 18.5–24.9 · Overweight 25–29.9 · Obese ≥ 30.
Worked examples
Tips
- Athletes with high muscle mass may show a higher BMI without excess fat.
- BMI ranges differ for children and some ethnic groups — ask a clinician for personalized advice.
- Pair BMI with waist measurement and fitness level for a fuller picture.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy (normal) range by the WHO.
Is BMI accurate for everyone?
BMI is a screening tool, not a diagnosis. It can misclassify muscular people, pregnant women, older adults, and some ethnic groups.
How do I lower my BMI?
Sustainable calorie control, higher protein intake, strength training, and consistent activity help reduce body fat. Speak with a healthcare professional before major diet changes.