BMI Calculator- Calculate Your Body Mass Index

BMI Calculator calculates your Body Mass Index which is a measure of body fat score based on your weight and height for 18 years old or older. 

What is BMI (Body Mass Index)?

BMI is the measurement of a person’s leanness based on their height and weight and is intended to measure tissue mass. It is widely used as a general indicator of whether a person has a healthy body weight for height.

Specifically, the value obtained from the calculation of BMI is used to classify whether a person is underweight, normal weight, overweight, or obese based on the extent to which the value falls between.

These limitations of BMI vary depending on factors such as area and age and are sometimes further subdivided into sub-categories such as severely underweight or very severely obese.

Being overweight or underweight can have significant health effects, so while BMI is an incomplete measure of healthy body weight, it is a useful indicator of the need for any additional testing or action.

BMI table for adults

It is recommended by the World Health Organization (WHO) body weight based on BMI values for adults. It is used for both men and women, ages 18 or older.

Classification BMI Score
Underweight Less than 18.5
Normal weight 18.5 to 24.9
Overweight 25 to 29.9
Obesity (Class 1) 30 to 34.9
Obesity (Class 2) 35 to 39.9
Extreme obesity 40+

How BMI is calculated?

BMI can be calculated by using these formulas:

BMI=(Weight in kg) / (Height² in m) [Formula for Metric Units]

BMI=(703*Weight in lbs) / (Height² in inches) [Formula for Imperial Units]

Limitations of BMI

Age and sex

For adults 18 or older, BMI covers weight and height but does not take into account age or sex.

A woman has more body fat than a man with the same BMI. Similarly, a larger person has more body fat than a smaller person with a similar BMI.

For these reasons, BMI may not provide the necessary details to determine whether a person’s weight is healthy.

Body composition

BMI does not reflect the location or amount of body fat, and these factors may affect health.

For example, people who have fat around their waist and abdominal organs may be at greater risk of health problems than those with fat in other areas.

Health relation

If a person has a high BMI, they are more likely to have a higher body fat ratio, especially if their BMI falls in the category of obesity.

Although it is possible to be “overweight” according to BMI, there is a healthy level of fat.

For people with an extreme muscle, such as athletes and bodybuilders, height and weight measurements alone may not give an accurate indication of health, because muscle weight is more than fat.

Development state

Regular BMI may not give an accurate indication of a person’s state of health at certain stages in life such as:

  • Pregnancy and breastfeeding
  • Childhood and adolescence while a person is still growing

For this reason, BMI counts are different for children and adolescents. These measurements take age and gender into consideration.