BMI World Health Organization Calculator

The Body Mass Index (BMI) is a widely used health metric developed by the World Health Organization (WHO) to assess whether a person's weight is within a healthy range for their height. This calculator provides an accurate way to compute your BMI and understand what the results mean.

What is BMI?

BMI stands for Body Mass Index, a numerical value derived from a person's weight and height. It's a simple screening tool used to categorize whether a person has a healthy body weight, underweight, overweight, or obesity based on their height and weight.

The WHO developed the BMI classification system as a global standard for assessing body weight. The most commonly used version is the adult BMI, which applies to people aged 20 and over. The pediatric BMI is used for children and adolescents.

The WHO BMI classifications are based on population statistics and are not intended to diagnose specific health conditions. Individual variations and body composition differences mean BMI should be used as a general guideline rather than an absolute measure of health.

How to Use This Calculator

Using this BMI calculator is simple:

Enter your height in the appropriate units (centimeters or feet/inches)
Enter your weight in the appropriate units (kilograms or pounds)
Click the "Calculate" button
View your BMI result and interpretation

The calculator will display your BMI value and provide a general interpretation based on the WHO standards. Remember that this is a screening tool and not a diagnostic measure.

BMI Formula

The BMI formula is straightforward:

BMI = Weight (kg) ÷ (Height (m) × Height (m))

For example, if you weigh 70 kilograms and are 1.75 meters tall:

BMI = 70 ÷ (1.75 × 1.75) = 22.86

This would classify as a normal weight according to the WHO standards.

Interpreting Your BMI

The WHO provides the following BMI categories for adults:

BMI Range	Classification
Below 18.5	Underweight
18.5 - 24.9	Normal weight
25 - 29.9	Overweight
30 and above	Obesity

For children and adolescents, the WHO uses different cutoffs. The calculator uses the adult BMI by default, but you can find pediatric BMI calculators in our health category.

Limitations of BMI

While BMI is a useful screening tool, it has several limitations:

It doesn't distinguish between muscle mass and fat mass
It doesn't account for body composition differences
It may not be accurate for athletes or people with high muscle mass
It doesn't consider other health factors like bone density or visceral fat
It may not be appropriate for certain populations, such as pregnant women or older adults

For a more comprehensive health assessment, consider combining BMI with other measurements like waist circumference, body fat percentage, and medical evaluations.

Frequently Asked Questions

Is BMI an accurate measure of health?

BMI is a useful screening tool but not a perfect measure of health. It doesn't account for muscle mass, body composition, or other health factors. For a more accurate assessment, consider combining BMI with other measurements and medical evaluations.

What is a healthy BMI range?

A healthy BMI range for adults is between 18.5 and 24.9 according to WHO standards. This range is considered normal weight. Values below 18.5 are considered underweight, and values above 24.9 are considered overweight or obese.

Can I use this calculator for children?

This calculator uses the adult BMI formula. For children and adolescents, you should use a pediatric BMI calculator which has different cutoffs based on age and sex. You can find pediatric BMI calculators in our health category.

What should I do if my BMI is in the overweight or obese range?

If your BMI is in the overweight or obese range, it's important to consult with a healthcare professional. They can provide personalized advice and help you develop a healthy lifestyle plan. This may include diet changes, exercise programs, and other lifestyle modifications.

Is BMI the same worldwide?

Yes, the BMI formula and classification system are standardized by the WHO and are used worldwide. This makes it a useful tool for comparing health metrics across different countries and populations.