World Health Organization BMI Calculator

The World Health Organization (WHO) Body Mass Index (BMI) calculator provides a simple way to assess whether your weight is appropriate for your height. BMI is a widely used indicator of whether an individual has a healthy body weight for their height.

What is BMI?

BMI stands for Body Mass Index. It is a measurement that uses a person's weight and height to estimate body fat. The formula for BMI is straightforward:

BMI Formula

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

The WHO uses BMI to categorize individuals into different weight status groups:

BMI Category	BMI Range	Weight Status
Underweight	Below 18.5	Potentially too low body weight
Normal weight	18.5–24.9	Healthy weight for height
Overweight	25–29.9	Potentially healthy weight
Obesity Class I	30–34.9	Moderately high body weight
Obesity Class II	35–39.9	Severely high body weight
Obesity Class III	40 and above	Very severely high body weight

BMI is not a perfect measure of body fat, but it provides a simple way to assess weight status. It's important to remember that BMI doesn't account for muscle mass, bone density, or distribution of fat, so it may not be accurate for athletes or older adults.

How to Use This Calculator

Using this BMI calculator is simple:

Enter your weight in kilograms or pounds in the weight field.
Enter your height in meters or feet/inches in the height field.
Click the "Calculate BMI" button to see your result.
Review the interpretation of your BMI result.

Example Calculation

If you weigh 70 kg and are 1.75 meters tall, your BMI would be calculated as follows:

BMI = 70 ÷ (1.75 × 1.75) = 22.86

This would place you in the "Normal weight" category.

The calculator will display your BMI value and categorize it according to the WHO standards. You can also see a visual representation of your BMI on the chart.

Interpreting Your BMI

Your BMI result provides a general indication of whether you are underweight, normal weight, overweight, or obese. Here's what each category means:

Underweight (BMI < 18.5): You may be at risk of nutritional deficiencies and other health problems. Consult a healthcare professional for advice.
Normal weight (BMI 18.5–24.9): Your weight is appropriate for your height. Maintain a healthy lifestyle to stay in this range.
Overweight (BMI 25–29.9): You may be at increased risk of developing health problems. Consider making lifestyle changes to reduce weight.
Obesity (BMI ≥ 30): You are at higher risk of developing serious health conditions. Consult a healthcare professional for personalized advice.

Remember that BMI is just one indicator of health. Other factors like muscle mass, bone density, and overall health should also be considered.

Limitations of BMI

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

It doesn't distinguish between fat and muscle mass.
It doesn't account for differences in body composition among people of the same height and weight.
It may not be accurate for athletes or older adults.
It doesn't consider the distribution of fat in the body.

Important Note

BMI is not a diagnostic tool. It should be used as a screening measure to identify potential health risks. For a complete assessment of your health, consult a healthcare professional.

For more accurate body composition analysis, consider using other methods like skinfold measurements, hydrostatic weighing, or dual-energy X-ray absorptiometry (DEXA).

Frequently Asked Questions

Is BMI an accurate measure of body fat?

No, BMI is not a perfect measure of body fat. It provides a general estimate but doesn't account for muscle mass, bone density, or fat distribution. For more accurate measurements, consider other methods.

What is a healthy BMI range?

A healthy BMI range according to the WHO is between 18.5 and 24.9. This range is considered normal weight for most adults.

Can BMI be used to diagnose health conditions?

No, BMI is not a diagnostic tool. It should be used as a screening measure to identify potential health risks. For a complete assessment, consult a healthcare professional.

How often should I check my BMI?

You can check your BMI as often as you like, but it's generally recommended to monitor it periodically, especially if you're making changes to your diet or exercise routine.

What should I do if my BMI is outside the normal range?

If your BMI is outside the normal range, consider making lifestyle changes such as eating a balanced diet and exercising regularly. Consult a healthcare professional for personalized advice.