BMI Calculator (Body Mass Index) with Tutorial
Table of Contents
What is BMI?
BMI, or Body Mass Index, is a numerical value derived from an individual's weight and height. It is a screening tool used to categorize individuals into various weight categories that may lead to health problems. However, it's important to note that BMI is not a diagnostic tool; it does not measure body fat directly nor does it account for muscle mass, bone density, overall body composition, and racial and sex differences. Instead, it can indicate whether a person is at a higher risk for health problems associated with being overweight or underweight.
BMI Formula
he formula to calculate BMI is simple and can be applied using either the metric system or the imperial system.
Metric System: BMI = weight (kg) / height^2 (m^2) Imperial System: BMI = weight (lbs) / height^2 (in^2) * 703
BMI Categories
The World Health Organization (WHO) categorizes BMI ranges as follows:
-Underweight : BMI less than 18.5
- Normal weight : BMI 18.5 to 24.9
- Overweight : BMI 25 to 29.9
- Obesity : BMI 30 or more
Understanding BMI
- Underweight (BMI < 18.5): Being underweight can be a sign you're not eating enough or you may be ill. If you're underweight, a GP can help.
- Normal weight (BMI 18.5–24.9): This range is considered healthy, and it is associated with a lower risk of chronic diseases and better overall health.
- Overweight (BMI 25–29.9): Being overweight is associated with an increased risk of several health conditions, including heart disease, high blood pressure, type 2 diabetes, and certain cancers.
- Obesity (BMI 30 or more): Obesity is linked to a significantly higher risk of health problems compared to being overweight. It requires lifestyle changes, and in some cases, medical intervention to reduce the risk of obesity-related diseases.
Limitations of BMI
While BMI is a useful general guideline, it has its limitations:
- Does Not Measure Body Fat Directly: BMI does not distinguish between excess fat, muscle, or bone mass, nor does it provide any indication of the distribution of fat among individuals.
- May Not Match Health Status: Some people may have a high BMI but not have excess body fat. For example, athletes can have a high BMI due to increased muscularity rather than increased body fat.
- Different for Children and Teens: BMI-for-age percentiles are used for individuals aged 2-19 years to account for age and gender differences in body composition.
