⚖️BMI Calculator

BMI Calculator online — quick and free

Our free BMI calculator lets you calculate your body mass index in seconds. Simply enter your height in centimetres and weight in kilograms — the result appears instantly with an interpretation based on World Health Organization (WHO) classification. You will also see a colour-coded BMI scale bar showing your position and the normal weight range for your height.

What does your BMI result mean?

BMI (Body Mass Index) is a simple measure of the ratio between weight and height. The WHO classification defines eight ranges: from starvation (below 16) through normal weight (18.5–24.99) up to obesity class III (40 and above). Keep in mind, however, that BMI is an indicative measure — it does not account for muscle mass, bone density, or fat distribution, and does not replace consultation with a doctor or dietitian.

Frequently asked questions

How is BMI calculated?

BMI (Body Mass Index) is calculated by dividing body weight in kilograms by the square of height in metres: BMI = weight [kg] / (height [m])². Our calculator does this automatically once you enter your height and weight.

What BMI is considered normal?

According to WHO classification, a normal weight corresponds to a BMI between 18.5 and 24.99. Below 18.5 indicates underweight or severe underweight; above 25 indicates overweight, and above 30 indicates obesity.

Is BMI a reliable health indicator?

BMI is an indicative measure. It does not account for body composition — for example, people with high muscle mass may have a high BMI despite being in excellent shape. For a comprehensive health assessment, consult a doctor or dietitian.

How does the adult BMI calculator differ from one for children?

This calculator uses the standard WHO classification for adults (18+). In children and adolescents, BMI is interpreted differently — taking age and sex into account — so results may be misleading for people under 18. Consult a paediatrician.