Body Mass Index (BMI) Calculator for Adults - Easily Measure Your Health
This calculator returns the Body Mass Index (BMI) and its associated classification based on the levels set by the World Health Organization. The calculator calculates BMI for both men and women.
| Body Mass Index (BMI) | Nutritional Status |
|---|---|
| Less than 18.5 | Underweight |
| 18.5–24.9 | Normal weight |
| 25.0–29.9 | Pre-obesity |
| 30.0–34.9 | Obesity class I |
| 35.0–39.9 | Obesity class II |
| 40 or more | Obesity class III |
| Source: World Health Organization | |
| Last Reviewed Date:28/02/2026 | |
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Calculate Body Mass Index (BMI) for Adults - Easily Measure Your Health
Body Mass Index (BMI), formerly known as the Quetelet Index, is a measure used to determine the nutritional status of adults. It is defined as a person's weight in kilograms divided by the square of their height in meters (kg/m²). For example, if an adult weighs 70 kg and is 1.75 meters tall, their BMI would be 22.9. 70 (kg) / 1.752 (m²) = 22.9 BMI For adults over the age of 20, the measurement of BMI falls into one of the categories mentioned in the table above.
BMI categories are based on the impact of excess fat in the body on diseases and mortality, and it is well-associated with fat management. BMI was developed as an indicator of the risk of developing diseases, as the risks increase with an increase in BMI. Some common conditions associated with excess weight and obesity include premature death, cardiovascular diseases, high blood pressure, joint dislocation, some types of cancer, and diabetes.
BMI is also recommended for use in children and teenagers. In the case of children, BMI is calculated in the same way as for adults, and then it is compared to z-scores or percentiles. During childhood and adolescence, the ratio between weight and height varies by gender and age, so the reference values that determine the nutritional status of individuals aged 0 to 19 years depend on gender and age. The reference points for BMI for age for the year 2006 for children aged 0 to 5 years to diagnose overweight and obesity are percentiles 97 and 99, respectively. For individuals aged 5 to 19 years, overweight is defined as a BMI value above +1.
Date:
Body Mass Index (BMI) is very easy to measure and calculate, making it the most commonly used tool to link health problems' risks to weight at the population level. It was developed by Adolphe Quetelet in the nineteenth century. In the 1970s, based on data and the report of the Seven Countries Study, researchers noticed that BMI seemed to be a good indicator of fat management and weight problems.
Like any other measurement, it is not perfect because it relies only on height and weight and does not take into account different levels of fat management based on age, levels of physical activity, and gender. For this reason, it is expected to exaggerate fat management in some cases and underestimate it in others.
Other measurements such as waist circumference (WC) can complement BMI estimates. However, linking waist circumference to health risks is not straightforward and should be done scientifically using appropriate techniques.
Benefits of Regular Physical Activity
Regular physical activity, such as walking, cycling, and dancing, has significant health benefits. For example, it can reduce the risk of heart and artery diseases, diabetes, osteoporosis, help with weight control, and promote mental well-being.
Participation in physical activity increases opportunities for social interaction and communication, enhancing cultural identity. Physical activity has a positive impact on both individuals and communities by promoting social interaction and cohesion.
Especially among children and young people, sports and other physical activities empower self-esteem and increase self-confidence. In addition, physical activity helps prevent and control risky behaviors such as tobacco and alcohol use, unhealthy eating, and violence.
Promoting physical activity also has a positive impact on the environment. For example, encouraging walking and cycling instead of motorized transport reduces traffic congestion, air and noise pollution, and fossil fuel consumption.
Benefits of a Balanced Diet
- Choosing a balanced and varied diet is an important step towards a happy and healthy lifestyle.
- Vitamins and minerals in the diet are essential for boosting immunity and healthy growth.
- A healthy diet can protect the human body from certain types of diseases, especially non-communicable diseases such as obesity, diabetes, heart diseases, and some types of cancer, and skeletal conditions.
- A healthy diet can also help maintain the appropriate body weight.
- Healthy nutrition is a good opportunity to enrich life by experiencing different foods from different cultures and sources, and in different ways of preparation.
- The benefits of consuming a variety of foods also include emotional aspects, as diversity and color are important elements of a balanced diet.
Source:World Health Organization
Last Review Date:31/05/2023
Frequently Asked Questions
What is Body Mass Index (BMI)?
How is Body Mass Index (BMI) calculated?
What are the Body Mass Index (BMI) categories?
- Less than 18.5: Underweight range
- 18.5 to 24.9: Healthy weight range
- 25.0 to 29.9: Overweight range
- 30.0 and above: Obesity range