BMI Calculator
Calculate Body Mass Index (BMI) from height and weight. Free, fast and private.
Formula: BMI = weight (kg) ÷ height (m)². Categories: under 18.5 Underweight, 18.5–24.9 Healthy, 25–29.9 Overweight, 30+ Obese. BMI is a screening guide only — it does not measure body fat or muscle, and it is not a medical diagnosis.
How to use BMI Calculator
- Enter your weight in kilograms.
- Enter your height in centimetres.
- Click Calculate BMI to see your BMI value, category and healthy weight range.
Note: this tool runs in your browser. Nothing is uploaded.
Frequently Asked Questions
What is a healthy BMI?
A BMI of 18.5 to 24.9 is generally classed as healthy weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
How is BMI calculated?
BMI = weight in kilograms divided by height in metres squared (kg/m²).
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so very muscular people, athletes, children and older adults should treat it as a rough guide only.
Is this BMI calculator free?
Yes, it is 100% free with no sign-up. Your data stays in your browser.