Children's BMI: Calculate and track weight index (calculator)

Children's BMI: Calculate and track weight index (calculator)

Is the child's body weight normal or does he/she weigh too little/too much for his/her age?
Enter the child's body values
The calculations are indicative

Calculator: BMI for children. Is the child overweight, ideal or underweight?

Why should we monitor BMI in children?

The answer is at risk of overweight, obesity and malnutrition.

In childhood, BMI has some peculiarities and is assessed differently.

Tracking body weight by BMI has its pitfalls. With the right approach, we can bounce back from this reading in children as well.

The BMI for adults takes into account height and weight. By correlating them, it estimates the level of body fat.

BMI does not measure subcutaneous and body fat, but the value reflects an approximate state in most cases.
The inaccuracy in the result should be taken into account in people with a high proportion of muscle mass.

In the childhood period, age, height and sex must be taken into account in addition to weight.

There are several differences between the sexes during development.

Height, weight and age are added to the specifics of the developmental period.

Why is this so?

This is because of the constant changes. The amount and distribution of adipose tissue across the body changes due to growth.

High or low body weight?

Too low or high values can be assessed by statistical data. These are obtained from percentile charts (similar to the growth curve, height and weight for age - link to calculator below).

The percentile charts, tables and results compare the child to the values of other children at the same age.

A single measurement is not an objective result.

Evaluation of the growth curve and growth dynamics of the child belongs to the hands of the pediatrician. The doctor assesses the development of the child on the basis of several examinations.

If necessary, medical examinations are carried out more frequently and the causes of deviations are sought.

Table with explanation of body weight percentiles in children over 2 years and adolescents (up to 18/20 years)

Status Value of the result
  • Result 5 percentiles or less
Normal/healthy body weight
  • Between 5th and 85th percentile
  • more than 85th percentile and less than 95th percentile
  • 95 percentile or more
Medium height/weight band
  • 25th-75th percentile = average growth trend
Extreme values
  • 97th and 3rd percentile - more frequent checks and monitoring of growth curve

The result is indicative of a statistic and not a health condition.

Percentiles are divided into multiple bands:

  • 97th percentile = child is heavier/higher than 97% and lighter/lower than 3% of children his/her age.
  • 95th percentile = 95% of children are shorter/lighter and 5% are taller/heavier
  • 90th percentile = 90% of children are shorter/lighter and 10% are taller/heavier
  • 75th percentile = 75% of children are shorter in height/weight and 25% are taller in height/weight
  • 50th percentile = 50% of children are taller/heavier and 50% are shorter/lighter
  • 25th percentile = child is taller/heavier than 25% and shorter/lighter than 75% of children
  • 10th percentile = child is taller/heavier than 10% and shorter/lighter than 90% of children his/her age
  • 5th percentile = 5% weigh less and 95% weigh more, same for height
  • 3rd percentile = 3% of children are shorter/lighter and 97% of children their age are taller/heavier
  • Mean height/weight band = 25th-75th percentile = average growth trend
  • Outliers = 97th and 3rd percentile - doctor suggests more frequent check-ups and monitor growth curve more frequently

Please note:
Percentiles are a statistical figure.
Dr. Khan says there is no ideal percentile. Healthy children are in every height and weight category. A child in the 5th percentile can be just as healthy as a child in the 95th percentile.

BMI is not a tool for diagnosing health problems or diseases. It is a tool for screening and monitoring a child's growth.

Back to overweight and obesity...

If a child takes in excessive amounts of energy (calories) over a long period of time, regardless of the body's need and consumption, the energy will be stored as fat stores.

Accumulating inches of fat negatively affects children and their health.

Here are some facts based on research:

  • 80% of obese children are obese in adulthood
  • 60% of children aged 5 to 17 have at least 1 risk factor for cardiovascular disease
  • 25% of children have two or more risk factors for cardiovascular disease
  • Worldwide, an estimated 155 million children and adolescents are overweight and obese
  • Overweight and obesity negatively affect health and are a risk for developing:
    • high blood pressure
    • high blood cholesterol levels
    • diabetes
    • asthma
    • sleep apnoea
    • joint and musculoskeletal disorders
    • liver damage
    • various types of cancer
    • psychological problems, stress, anxiety and depression
    • reduced self-esteem

Obesity, even in childhood, leads to atherosclerosis, metabolic syndrome and increased cardiovascular risk. Obese children have a risk of stroke and heart attack in adulthood (but at a significantly lower age).


In the case of malnutrition, it is similar. Inadequate intake of necessary nutrients, vitamins and minerals will negatively affect growth, height, weight and health.

Let us therefore not forget a sufficient exercise regime in children and a varied rational diet with sufficient drinking.

Children should grow up in a calm environment with reduced stress and with sufficient support from loved ones.

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Important notice:

Please remember that the results of our health calculators and analyzers are for guidance purposes only. They are not a substitute for a professional examination or the advice of a doctor, pharmacist or other health care professional.

Each person is unique, and everyone's needs may vary. Calculators and analyzers have limitations and do not provide a comprehensive individual view of health.

Their use is at your own risk. Neither the site operator nor the author is responsible for misuse and misinterpretation of information obtained through their use. By using the calculators and analyzers, you agree to these terms and conditions and neither the operator nor the author shall be liable for any consequences.

You are advised to consult a professional for your medical condition. Remember that health is an important topic and any decisions should be made in consultation with a professional.

This calculator/analyzer is not a medical tool or medical aid. Consult your doctor about your health problem.

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