BMI Calculator Online — Body Mass Index Free Tool
Enter your weight and height to get your Body Mass Index and its health category — plus the healthy weight range for your height.
BMI Calculator
Enter weight and height to get your Body Mass Index and its health category — for adults.
- Your BMI
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- Category
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- Healthy range for you
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BMI is a guide only — it does not measure muscle, bone density or body fat. Ask a clinician for personal advice.
How to use it
- Enter weight in kilograms and height in centimetres.
- Tap “Calculate BMI”.
- Read your BMI, category and healthy weight range.
Frequently asked questions
What is BMI?
Body Mass Index = weight in kg ÷ height in metres squared. It is a screening guide, not a diagnosis.
What are the categories?
Under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obese (WHO ranges for adults).
Is BMI accurate for athletes?
Not always — muscle weighs more than fat, so very muscular people can score “overweight” while being healthy.
Should I trust the result alone?
No — BMI is one signal. Waist size, blood pressure and a clinician's view matter too.
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