BMI Calculator
Enter weight and height – see your category instantly
Basis: WHO classification for adultsCalculated in your browser – your inputs are not transmitted and are kept on this device only if you choose
For whom?
Tap to type · drag sideways to adjust
In centimetres, e.g. 180 for 1.80 m.
Check a target weightOptional
Shows the BMI at this weight as a mark on the scale.
Your BMI
24.69
24.69According to the WHO classification for adults, a BMI of 24.69 falls in the Normal weight range (18.5 – 24.9).
- Normal weight at 180 cm
- 60 to under 81 kg
BMI is a statistical reference value and does not replace a medical examination. It accounts for neither muscle mass nor body build. Different thresholds partly apply to children, adolescents and older adults.
How this was calculated
WHO classification for adults
- Underweight
- < 18.5
- Normal weight
- 18.5 – 24.9
- Overweight
- 25 – 29.9
- Obesity
- ≥ 30
Source: WHO fact sheet “Obesity and overweight” – adults: overweight from BMI 25, obesity from 30.
RZ-26 · headon.pro
What does BMI tell you?
Meaning, formula and WHO classification explained simply
The Body Mass Index (BMI) is the most widely used reference value worldwide for assessing whether a person’s body weight, relative to their height, is normal, too low, or too high. The World Health Organization (WHO) has defined four main categories based on BMI: underweight (BMI below 18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9), and obesity (30 and above). This classification has become internationally established in epidemiology and clinical medicine because it is simple to calculate and correlates statistically well with the risk of certain diseases.
The BMI formula is: BMI = body weight (kg) / (height in meters)². For a person weighing 80 kg with a height of 1.80 m, this gives: 80 / (1.80 × 1.80) = 80 / 3.24 ≈ 24.69. This value falls within the normal range. Our calculator performs this calculation automatically as soon as you enter your weight (kg) and height (cm).
An important point: BMI is a statistical population reference value, not an individual diagnostic tool. It accounts for neither muscle mass nor body composition, age, or ethnicity. Strength athletes can have an “elevated” BMI despite a low body fat percentage, because muscle is heavier than fat. Conversely, a normal BMI combined with low muscle mass and high body fat (so-called “normal-weight obesity”) can be misleading. For a well-founded health assessment, further measurements such as waist circumference, body fat percentage, and blood tests are advisable.
In Germany, according to the Federal Statistical Office, a significant share of the population is classified as overweight (BMI ≥ 25). Being overweight, and obesity in particular, increases the risk of type 2 diabetes, high blood pressure, coronary heart disease, stroke, and certain types of cancer. Even a moderate weight loss of 5–10% of body weight can measurably lower this health risk. Being underweight (BMI below 18.5) is also risky and can indicate malnutrition, eating disorders, or serious underlying conditions.
WHO classification at a glance
BMI categories according to WHO
- Underweight: BMI < 18.5
- Possible malnutrition; increased risk of bone loss and heart problems. Medical evaluation recommended.
- Normal weight: BMI 18.5 – 24.9
- The healthiest range according to the WHO. Lowest statistical risk of weight-related diseases.
- Overweight: BMI 25 – 29.9
- Slightly increased risk of cardiovascular disease and diabetes. Prevention through diet and exercise recommended.
- Obesity: BMI ≥ 30
- Significantly increased health risk. Class I (30–34.9), Class II (35–39.9), Class III (≥ 40). Medical supervision important.
Calculation examples
- Weight
- 80 kg
- Height
- 1.80 m
- BMI = 80 / (1.80)²
- 24.69
- Category
- Normal weight
- Weight
- 95 kg
- Height
- 1.75 m
- BMI = 95 / (1.75)²
- 31.02
- Category
- Obesity (Class I)
Frequently asked questions about the BMI calculator
WHO classification, health risks and limits of BMI
What is BMI and how is it calculated?
The Body Mass Index (BMI) is a measure that relates body weight to height. The formula is: BMI = weight (kg) divided by height (m) squared. For example: a person weighing 75 kg with a height of 1.75 m has a BMI of 75 / (1.75 × 1.75) = 24.49. Based on this value, the World Health Organization (WHO) has defined categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9), and obesity (30 and above).
What is a normal BMI for adults?
According to the WHO definition, a BMI between 18.5 and 24.9 is considered normal weight for adults. This range is associated with the lowest statistical risk of weight-related diseases such as cardiovascular disease or type 2 diabetes. Values between 25 and 29.9 indicate overweight, and 30 and above is classified as obesity (Class I). Different reference values apply to children, adolescents, and seniors.
Is BMI equally meaningful for everyone?
No. BMI has well-known limitations: it does not distinguish between muscle mass and fat mass. Athletes with a lot of muscle mass can have an elevated BMI even though their body fat percentage is low. Different reference values also apply to older adults, pregnant women, and people of Asian or African descent. BMI is a statistical population reference value, not an individual diagnostic tool. For a personal assessment, a medical examination is always recommended.
At what BMI does a health risk exist?
From a BMI of 25, the statistical risk of diseases such as type 2 diabetes, high blood pressure, and heart disease rises slightly. From BMI 30 (obesity Class I), the risk is markedly increased; from BMI 35 (obesity Class II), it is strongly increased; and from BMI 40 (obesity Class III, formerly “morbid obesity”), it is very strongly increased. Being underweight (below 18.5) carries risks of malnutrition, bone loss, and cardiac arrhythmia.
How can I lower my BMI?
A sustainable BMI reduction for those who are overweight works best through a combination of a calorie-reduced, balanced diet and regular physical activity. Nutrition experts recommend a moderate calorie deficit of 300–500 kcal per day, combined with at least 150 minutes of moderate exercise per week. Radical diets often lead to the yo-yo effect. If your BMI is above 30, you should seek medical support.