Body Mass Index (BMI) Calculator

What is BMI?

BMI, or Body Mass Index, is a measurement that assesses your body weight relative to your height. The BMI measurement can be used for any age, from babies and children to teens and adults. Such a measurement, which classifies individuals as underweight, normal weight or overweight, can be used to determine if someone is an inappropriate or unhealthy weight for their current size. BMI calculators can be ideally incorporated for men and women alike when setting fitness goals. BMI calculation can play a significant role in observing weight development, and is today's preferred method over other health indicators, such as size or weight.

How to calculate BMI

To calculate BMI, a body mass index calculator can be used. Our free, online BMI calculator utilizes a scientifically recognized formula to yield easy-to-read results that can help you better understand both your current BMI and your ideal weight. The metric formula we use to calculate BMI is as follows: m/l². Here, we take your current body weight in kilograms and divide it by the square root of your height in meters. In addition, our BMI calculator also incorporates your age and sex. By doing so, the BMI calculator is ideal for kids, teens, men and women. Taking these variables into account, we calculate BMI and display the results by means of graphical analysis.

Factors influencing BMI

The aforementioned factors included in our body mass index calculator are essential when calculating BMI. Age and gender, for example, play a significant role in yielding appropriate values. Since men tend to have a higher muscle percentage than women, the BMI for men is also generally higher than the BMI for women. Healthy BMI values are also significantly higher for older individuals compared to kids, teens or younger individuals. Other factors influencing the calculation of BMI include elements such as daily activity, body type and even amputation. There is indeed a significant difference in whether someone has a high fat or high muscle percentage, as fat is generally responsible for obesity. This distinction, in addition to others, can be considered when you calculate BMI. However, in order to make our online BMI calculator as simple and user-friendly as possible,we have chosen to emit this information.

Properly classifying BMI

So, how does one actually sort through and understand the calculated values from the YAZIO BMI calculator? Depending on your gender, age and other varying factors, your BMI is categorized as either underweight, normal, overweight or even obese (excess weight). In addition to your current measured body value, our online BMI calculator also indicates your body's ideal weight and BMI range. According to the World Health Organization, a healthy BMI range for adults is classified as 18.5–24.9. This can be calculated by taking the weight in kilograms and dividing it by the height in meters squared (kg/m²). This is a standard calculation used for both adult males and females since the equation only takes gender into consideration for children and adolescents. Any number under 18.5 indicates being underweight and any number over 24.9 indicates the individual may be entering obesity levels. The range of 18.5–24.9 represents what would be considered a “normal, healthy weight” for the individual. Of course, this isn’t a completely perfect equation as several other factors come into play when determining the health of an individual. Some factors that may affect this BMI equation include muscle mass, age and gender. It can be helpful to use the BMI as just one screening tool for understanding your overall health, while also taking into account your own personal wellness needs. As of 2022, the World Health Organization found that more than 1 billion people around the world are classified as obese, of which 650 million were adults, 340 million adolescents and 39 million children. With insights into current statistics and BMI calculations, parents can have a better understanding of their children’s health and can better observe their weight development.

Consequences of high or low BMI

With high BMI values, severe health conditions are expected. Not only does obesity restrict a person's physical movement, but it also increases the chances of suffering from secondary diseases. Obesity increases the risk of diabetes and can lead to increased blood pressure and signs of hypertension (high blood pressure). It can also result in dyslipidemia and high blood lipids. With a BMI of over 30 or even 40, the risk of suffering from a heart attack or stroke is significantly increased. Patients with obesity often times must deal with osteoarthritis, gallbladder disease or hormonal imbalances. Risks of various forms of cancer, such as colon or kidney cancer, are also increased.

A BMI with a strong indication of being underweight can also be extremely dangerous. Here the biggest problem is generally a lack of essential nutrients and resulting deficiencies. Nutrient deficiency can contribute to the development of osteoporosis and can affect muscle function. Individuals who are underweight often have weaker immune systems, making them more susceptible to infectious diseases and making it more difficult for wounds to heal. These serious deficiencies can result from eating disorders, such as anorexia. Such disorders have extremely negative effects on bones, teeth and the immune system as a whole. In worst cases, the threat of cardiac arrhythmia caused by potassium deficiency is present.

Is a BMI calculator still relevant?

Criticism of BMI calculators is increasingly present. Such criticism stems from the fundamental question of whether or not a simple BMI value higher than 24 can immediately indicate potential medical problems. Rather, critics are wanting to focus more and more frequently on the complete composition of an individual's weight. This is especially relevant for athletes, in which higher weight resulting from increased muscle mass, and consequently a higher BMI, does not indicate health problems. Furthermore, even those individuals who have a higher body fat can vary from case to case. A study from the Medical Clinic of Munich's Ludwig Maximilian University, for example, distinguished between belly fat and so-called lower body fat. While the latter is safe on thighs, buttocks or arms, fat around the abdomen can increase the risk of cardiovascular disease and stroke. For simplicity purposes, such factors are not included in our BMI calculator.

Inconsistencies among researchers

In addition to questions of weight composition and variations among individuals with differing lifestyles, there are also growing inconsistencies among researchers. While many studies bring attention to specific consequences of extremely high BMI like stroke, heart attack or death, for example, the aforementioned Munich-based study makes no mention of such consequences. Inconsistencies can also be found in regards to classification levels. Recently, experts have decreased the value for so-called underweight individuals. As a result, healthy individuals may unnecessarily end up falling into the overweight category, as in the case of athletes. Such inconsistencies bring into question the necessity of such a measuring method, as well as its accuracy.