BMI Calculator: Calculate your Body Mass Index

What is my BMI? Photo: kenary820 / (2)

In this article you can calculate your BMI. In addition, we clarify all questions about body mass index.

Body mass index gives you a first impression of whether you are normal, overweight or underweight. This is especially useful if you are unsure of your own body weight. Our adult BMI calculator calculates BMI for both women and men. Unfortunately, the calculator is not suitable for children and teenagers due to the changes in the relationship between growth and height.


Body mass index is a value that gives an indication of whether your body is in a medically healthy state. Age, weight, height and gender can be used to assess whether you are, for example, underweight or overweight.

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The formula for the BMI calculator consists of the ratio between body weight and height. The body weight in kilograms is divided by the square of the height in meters. So the formula is as follows:

BMI = body weight: (height * height)

Example: A person is 1.85 m tall and weighs 82 kg.

BMI = 82 : (1.85 * 1.85)

BMI = 23.9

The BMI for this person is 23.9 in this example.

The World Health Organization (WHO) classifies body mass index values ​​into six different classes:


nutritional status

Under 18.5


18.5 – 24.9

normal weight

25.0 – 29.9


30.0 – 34.9

Class I obesity

35.0 – 39.9

Class II obesity

Over 40

Class III obesity

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BMI was developed as a risk indicator for diseases and is well associated with obesity. A value of around 30 or more can lead to health problems. The WHO says that as BMI increases, the risk of some diseases increases, such as cardiovascular disease, high blood pressure, osteoarthritis, cancer, diabetes and premature death. However, it is also possible that your body is not in an overweight state, but still shows a value above 30. The reasons for this can be found in the next section. The German Society for Nutrition therefore recommends regular medical examinations.

Age plays an important role in the BMI calculator, as normal weight changes with age. For example, the metabolism changes from the age of 40, which is why the normal weight moves upwards. The following table shows which BMI is classified as ideal at which age:

age ideal BMI
19 – 24 19 – 24
25 – 34 20 – 25
35 – 44 21 – 26
45 – 54 22 – 27
55 – 65 23 – 28

Source: NRC, Diet and health. Implications for Reducing the Risk of Chronic Diseases (1989)

In addition to body weight, the distribution of adipose tissue is also crucial for health. The German Society for Nutrition distinguishes between men and women. An increased accumulation of fatty tissue in the abdomen can pose significantly more risks in relation to cardiovascular diseases than in the hips. The table below shows the waist circumference limits for an increased risk:

waist width

Higher risk

Markedly increased risk


≥ 94 cm

≥ 102 cm


≥ 80 cm

≥ 88 cm

BMI is an easy way to quickly assess your body weight. However, it has its limitations and weaknesses that should definitely be taken into account.

  • The BMI calculator does not take anyone into account muscle mass. Since muscle is heavier than fat, depending on their mass, the BMI calculator is wrong. It may be that athletes in general (especially strength athletes or bodybuilders) are considered obese according to BMI, even though they are not. Actor and ex-wrestler Dwayne “The Rock” Johnson is known for his massive muscle mass, for example he has a BMI of 30.72. According to BMI, he would therefore be very overweight.
  • That too exercise habits is not taken into account in the BMI calculator. For example, slightly overweight people who play sports are significantly healthier than normal weight people who do not play sports.
  • Like muscle mass, Fat distribution and stature not included in the BMI calculator. However, this is particularly important in case of later possible diseases (see above).

The BMI calculator gives you a quick way to estimate your weight. However, you should be aware of the limitations and weaknesses of the BMI method mentioned above and consult a doctor for a detailed diagnosis.

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