BMI Calculator
Work out your Body Mass Index from your weight and height, with the WHO category.
- Category
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- Healthy weight range
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What is BMI?
Body Mass Index (BMI) is a simple screening number that relates your weight to
your height. It is calculated as weight ÷ height² (kilograms and metres) and is used
by the WHO to place adults into broad weight categories.
How to read your result
A BMI under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight and 30 or above is obese. BMI does not distinguish muscle from fat, so very muscular people may read as "overweight" despite low body fat.
Note: BMI is a general screening tool, not a diagnosis. This calculator does not provide medical advice — talk to a qualified healthcare professional about your individual health.
How to use the BMI Calculator
- Enter your weight. Type your body weight in kilograms.
- Enter your height. Type your height in centimetres.
- Read your BMI. See your BMI value and WHO category update instantly.
- Check the healthy range. Compare against the healthy-weight range shown for your height.
Frequently asked questions
Is BMI accurate for athletes?
Not always. BMI counts muscle and fat the same way, so athletes with high muscle mass can score as overweight despite being lean and healthy.
What is a healthy BMI?
For most adults a BMI between 18.5 and 24.9 is considered the healthy range. Ideal targets can differ by age, ethnicity and body composition.
Does this calculator store my data?
No. Everything is calculated in your browser; nothing you enter is sent to or stored on a server.
Should I use BMI to make health decisions?
Use it as a rough guide only. It is not a substitute for professional medical assessment, which can include waist size, body-fat percentage and other factors.