Body Mass Index (BMI) Calculation: The Easiest Way to Find Out Your Healthy Weight

What is Body Mass Index?

Body Mass Index (BMI) is a simple but effective measure that evaluates the suitability of a person’s weight according to their height. This method, which is also accepted by the World Health Organization (WHO), is used to determine obesity, underweight or ideal weight status.

How to Calculate BMI?

The formula is pretty simple:

📌 BMI = Weight (kg) / Height (m)²

Example:
If your weight is 70 kg and your height is 1.75 m;
BMI = 70 / (1.75 x 1.75) = 22.86

What are the Height Weight Index Values?

Body mass index (BMI), commonly known as the “height-weight index” among the public, measures the suitability of a person’s body weight according to their height. The result obtained after calculating the BMI is evaluated at certain intervals. Each interval shows the level at which the person’s weight is in terms of health:

BMI Value (kg/m²)MeaningUnder 18.5Thin18.5 – 24.9Normal (ideal weight)25.0 – 29.9Overweight30.0 – 34.91st degree obesity35.0 – 39.92nd degree obesity40.0 and aboveMorbidly obese

These values ​​are determined according to general public health criteria. A BMI between 18.5-24.9 reduces the risk of chronic diseases such as cardiovascular disease, diabetes and joint problems. However, this value range may not mean “ideal health status” for everyone; BMI may be high in individuals with high muscle mass, such as athletes, but this does not mean excess fat. Therefore, the person’s general health status should also be taken into consideration when evaluating BMI.

Why Is Body Mass Index Important?

BMI is an important tool in assessing health risks for:

• Heart diseases
  
• Type 2 diabetes
  
• Hypertension
  
• Stroke (paralysis)
  
• Sleep apnea
  
• Some types of cancer
  
• Hormonal disorders
  

A high BMI may mean that you are at increased risk of developing these diseases. However, a low BMI can also lead to conditions such as weakened immunity, muscle loss, and decreased bone density.

What Should Body Mass Index Be According to Age?

Although the Body Mass Index calculation is basically based on the same formula regardless of age, interpretation may differ depending on age, as body structure, fat percentage and metabolic rate change with age.

• Children and Adolescents (2-18 years old)

In this age group, BMI is not evaluated alone. Children’s BMI is evaluated according to age and gender-based percentile curves.

• Between 5th and 85th percentile: Normal

• 85 – 95th percentile: Overweight

• 95th percentile and above: Obese

These evaluations should be made by pediatric specialists.

• Adults (18-65 years old)

The general BMI classification is valid for this age group. However, as age progresses, muscle mass may decrease and fat percentage may increase. Waist circumference measurement is also an important criterion, especially for individuals over 50 years of age.

• Age 65 and Above

In older ages, very low BMI values ​​(e.g. below 20) are associated with malnutrition, muscle loss, and risk of falls. Therefore, a slightly higher BMI in older ages (e.g. between 23 and 27) may be considered protective in terms of health.

What Should You Consider Besides Body Mass Index?

Your Body Mass Index value alone doesn’t tell you everything about your health. The following metrics should also be taken into consideration:

• Waist circumference measurement: Fat accumulated around the abdomen increases cardiovascular risks.
• Fat-muscle ratio: Even though BMI is high in individuals who do sports, their fat ratio may be low.
• Eating habits and physical activity level
• Genetic factors and chronic disease history

Therefore, Body Mass Index is a starting point; it should be supported by individual health assessments.