About BMI

BMI is an abbreviation of Body Mass Index and is used internationally to indicate, among other things, a person’s ideal weight. The calculations are based on a person’s height and weight. The formula suggests where on the scale, underweight-normal-overweight, an individual belongs.

About BMI

The formula reads:

BMI = weight in kg / (height in meters)²

Calculating BMI using pounds (lbs) and inches (in) is done in a similar way, but the result is multiplied with a conversion factor of 703.

BMI = ( weight in lbs / (height in inches)² ) × 703

BMI categories

There are five to eight different BMI zones or ranges. Here we have chosen to use six categories. These six have been established and used by the World Health Organization (WHO) and are:

Under 18,5Underweight
18,5 – 25Normal weight
25 – 30Overweight
30 – 35Significant overweight (obesity class 1)
35 – 40Severe overweight (obesity class 2)
Over 40Extreme overweight (obesity class 3)

BMI Scale Exceptions

A person’s BMI is calculated based on his or her physical dimensions. Not all individuals’ results agree as the calculation will not always display the correct value. This will, for example, be the case for unusually tall people, as well as bodybuilders with a lot of muscle to the proportion of body fat.

Using a standardized BMI scale, those results will not be considered accurate. Children of a certain age, especially those who are still growing, will also not fit into the standardized BMI table, and of course, pregnant women as well.

Ideal weight

Each individual responds differently to weight gain or weight loss. Some find it easier to change their weight, while others find it more challenging to achieve a perfect weight. If you deviate a lot from the ideal weight, be careful about your diet and health. If you are too far away from what is considered to be perfect on the BMI rating, then we recommend that you seek medical advice.

Waist-Hip Ratio

There are other ways to measure your body fat ratio than just height and weight. To obtain a more accurate result over one’s health condition, one can also choose to use WHR, an abbreviation of Waist-Hip-Ratio.

First, measure the waist circumference at its narrowest point, then measure the hip where it is at its fullest. Then divide the waist circumference with the hip measurement. The proportion of these measurements delivers the answer. Men are at risk if the result exceeds 0.9. For women, it should be less than 0.7


The location of the excess fat on the body plays a significant role in how severe the health risk is. Abdominal fat is significantly more critical. Fat evenly distributed on other parts of the body is less dangerous.

With a BMI value above 27, the risk of obesity-related diseases increases significantly. That is especially true if the waist measure exceeds the values given in the table below.

Waist size menWaist size women
Low riskUnder 92Under 79
Moderate risk93 – 10080 – 87
High riskOver 101Over 88

Intervals in the scale

BMI has evolved to become a risk indicator for certain diseases. The ranges are based on the increasing negative effect that body fat has on illnesses and deaths. These intervals are relatively well documented and relate to the proportion of body fat. With increased BMI, there is also an increased risk of certain overweight-related diseases. These are mainly:

  • Heart disease
  • Blood vessel disorder
  • Hypertension
  • Diabetes
  • Arthritis
  • Various forms of cancer
  • Early death

Our recommendations on BMI

Our comments and recommendations show results derived from the average population. The suggestions are not individually or personally adapted. In case of uncertainty about health status, we recommend that the reader consult a healthcare professional. Advice from a qualified physician can give you more accurate assessments.