Who BMI for Age 0-5 Calculator

This calculator helps you determine the Body Mass Index (BMI) for children aged 0-5 using the World Health Organization (WHO) growth standards. BMI is a measure of body fat based on height and weight that applies to most adults, but the WHO provides specific growth charts for children.

What is WHO BMI for Age 0-5?

The World Health Organization (WHO) provides growth charts for children aged 0-5 that show the expected weight-for-age, weight-for-height, and height-for-age. These charts help healthcare providers monitor a child's growth and development.

BMI for children is calculated differently than for adults. The WHO uses specific formulas and growth standards to assess a child's nutritional status. The BMI-for-age z-score is a common measure that compares a child's BMI to the median BMI of children of the same age and sex.

The WHO BMI-for-age z-score is calculated as:

(Child's BMI - Median BMI for age/sex) / Standard deviation of BMI for age/sex

This z-score helps identify children who are underweight, overweight, or obese compared to their peers. A z-score of -2 or below indicates underweight, while a z-score of +2 or above indicates overweight or obese.

How to Use This Calculator

To use this calculator:

Enter the child's age in years and months
Select the child's sex (male or female)
Enter the child's height in centimeters
Enter the child's weight in kilograms
Click "Calculate" to see the results

The calculator will display the child's BMI and compare it to WHO growth standards. It will also show the BMI-for-age z-score and provide an interpretation of the results.

BMI = weight (kg) / (height (m))²

For example, a 2-year-old girl who is 85 cm tall and weighs 12 kg would have a BMI of:

12 / (0.85 × 0.85) = 16.7

Interpreting WHO BMI Results

The WHO growth charts provide reference values for BMI-for-age z-scores. Here's what the different z-score ranges mean:

Z-score Range	Interpretation
Below -2	Underweight
-2 to -1	Low weight for age
-1 to +1	Normal weight for age
+1 to +2	High weight for age
Above +2	Overweight or obese

It's important to note that BMI alone doesn't diagnose an eating disorder or malnutrition. Other factors like muscle mass, body composition, and overall health should be considered.

Limitations of WHO BMI

While BMI is a useful screening tool, it has some limitations when applied to children:

BMI doesn't account for muscle mass, which is higher in children than in adults
It may not be accurate for very young infants or premature babies
BMI doesn't measure body fat percentage directly
It doesn't account for ethnic differences in body composition

For more accurate assessments, healthcare providers may use other measures like skinfold thickness, waist-to-height ratio, or dual-energy X-ray absorptiometry (DEXA) scans.

Frequently Asked Questions

What is the difference between BMI and BMI-for-age?

BMI is a general measure of body fat based on height and weight that applies to most adults. BMI-for-age is a more specific measure that compares a child's BMI to the median BMI of children of the same age and sex, using WHO growth standards.

Is BMI-for-age the same as BMI percentile?

No, BMI-for-age is different from BMI percentile. BMI-for-age uses z-scores to compare a child's BMI to the median BMI of children of the same age and sex, while BMI percentile directly compares a child's BMI to the distribution of BMIs for children of the same age and sex.

What should I do if my child's BMI-for-age z-score is outside the normal range?

If your child's BMI-for-age z-score is outside the normal range (-2 to +2), you should consult with a healthcare provider. They can help determine if the result indicates an underlying health condition or if other factors are influencing the measurement.