BMI Calculator

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BMI calculator

This free BMI calculator works out your body mass index from your height and weight. Type your numbers in kilograms and centimetres and the result updates on the screen. Nothing is sent anywhere.

Height (cm)

Weight (kg)

Enter your height and weight to see your body mass index.

What this result means

Body mass index (BMI) compares your weight with your height using the standard formula weight in kilograms divided by height in metres squared.

BMI	Common category
Below 18.5	Underweight range
18.5 to 24.9	Healthy weight range
25.0 to 29.9	Overweight range
30.0 and above	Obese range

A single BMI number is only a rough guide. BMI ignores muscle and body shape. A muscular person and a person with a lot of body fat can share the same BMI. It also does not show where fat sits on the body, which matters for health. Waist size and overall fitness matter too.

Limits and when to see a doctor

BMI is a screening number, not a diagnosis. It is less reliable for athletes, for people with a lot of muscle, for older adults who have lost muscle, and for children, who use age and sex specific charts instead. If your BMI is far outside the healthy range, or if you have diabetes, high blood pressure, or a heart condition, speak with a doctor before acting on it.