What is Body Mass Index (BMI) – Calculation and Meaning

Body Mass Index (BMI) is used globally to categorize the body weight of adults. It is a simple and quick way to figure out, if an adult’s weight is within normal limits or not. BMI is just the first signal of what is going on with body weight.

It is important to emphasize that body weight is not indicative of body composition. Though many consider their BMI as an indication of whether they are overweight or not.

In fact more important is the percent of fat in our body composition. For example, an athlete based on the Body Mass Index may seem overweight, but his body fat percentage is too small and the muscle mass increased due to exercise. Conversely, a sedentary person may be at normal body weight but the body fat percentage is increased.

Body Mass Index is therefore a simple and easy-to-use tool for assessing obesity, but it does not provide information on the amount and distribution of fat. Therefore, it is a reliable quantitative but not qualitative marker because it does not take into account body composition, which requires lipometry.

How to calculate your BMI

BMI is calculated with the following mathematical expression.

It’s the quotient of body weight (in kilograms) to the height square (in meters).

BMI mathematical expression

BMI ranges - Body mass index

BMI categories meaning

Low – BMI below 18.5

Adults with BMI below 18.5 are consider underweight with a lower body weight than normal. They are often malnourished or suffer from a some kind of metabolic disorder. They should improve their eating habits as this is likely to have serious and negative impacts on their health. A visit to an expert nutritionist or doctor is definitely a must.

Normal – BMI between 18.5 and 25

Normal is the BMI category of adults who have the ideal weight in relation to their height and therefore they have to only maintain that weight. The only thing to do is to keep their current eating habits forever.

Overweight – BMI between 25 and 30

Adults in this category are considered overweight people who have some deviation from normal weight and should watch their diet to reach their normal weight and not switch to obesity. There is no major danger for their health, although they have to be very careful.

Obese (Level 1) – BMI between 30 and 35

Obese 1 st level are people with a much higher weight than normal and have an increased risk of developing cardiovascular disease, diabetes mellitus, stroke and many other obesity related conditions. They must therefore regulate their weight.

Obese (Level 2) – BMI between 35 and 40

In this category applies the same as obese level 1, but with even more increased risk of developing diseases related to overweight.

Obese (Level 3) – BMI over 40

People with BMI over 40 are considered to be in a critical situation. They should seek immediate help, because their health is in danger.

Standard BMI Calculator

Fill in your Height and Weight below and calculate your Body Mass Index (BMI).