BMI calculator

What is BMI?

Body Mass Index (BMI) is a measure primarily used to define overweight and obesity, using the relationship between weight and height to classify you into a group (see below).

BMI range

BMI Category
< 15 Very seriously underweight
15 - 16 Very Underweight
16 - 18.5 Underweight
18.5 - 25 Normal (healthy weight)
25- 30 Overweight
30 - 35 Obesity class I (mild obesity)
35 - 40 Obesity class II (severe obesity)
> 40 Obesity class III (very severe obesity)

BMI and its reliability

BMI does not take individual factors into account when calculating your BMI, the most common argument against the formula is that it does not differentiate between muscle and fat.

Muscle has a much higher density than fat, so very muscular people such as powerlifters and athletes can be at a healthy weight even though the BMI indicates obesity.

If you want a more reliable answer about your weight, we advise you to see a doctor as they will most likely make a more individual assessment.

BMI calculation

BMI is a mathematical formula that divides a person's height by the squared length of their body in metres (kg/m2) to arrive at a BMI number.
A normal BMI is between 18.5 and 25. This indicates that the person is within the normal weight range for their height.