How to Use Adult BMI Calculator According to Age and Sex

BMI calculator

Before we discuss the BMI calculator, let us take a few minutes to define BMI and also know what the Body Mass Index (BMI) is all about, because you probably would want to know the meaning of the BMI.

What is BMI

The Body Mass Index popularly called BMI is a form of individual weight in kilogram which is divided by the square of the person height in meters, The BMI is not expensive and a simple and smart screening procedure for weight classes such as overweight, underweight, health weight as well as obesity

It’s worthy to note that the BMI doesn’t measure the human body fat directly, however the BMI is relatively correlated with more direct measurement of body fat. Nevertheless the BMI is to be very much correlated with different metabolic and disease outcomes since these are direct in the measurement of the body fat and weight

The BMI Calculator

What is a BMI calculator? The BMI Calculator can is use in calculating the BMI values and its corresponding weight designation and status while taking age and sex  into consideration. are discussed below in detail. In a dimplier term,the BMI calculator is a simple tool that computes an individual body mass index and carefully rates the BMI for men, women, children, teens and adults.

 The SBMI – is an index that was developed about four (4)years ago mainly for this calculator – serves this purpose. It was  based on the results of the most detailed study  published so far on the BMI and its associated health risks

<<<<<Calculate Your BMI Here – Standard BMI Calculator>>>>>

BMI Calculator for Kids

BMI calculator for kids teens, as help to understand that a high Body-Mass-Index (BMI) can lead to weight related problems and diseases, on the hand that is underweight stands the risk of related problems. Unlike adults, the BMI for children is age and sex or gender. Its important to note that the  is expressed in percentile that the child fits in according to age and sex. 

The BMI calculator Kids is used to provide the body mass index (BMI) and the correlating BMI for age percent based on CDC growth charts for young children and kids of ages between 2 years to 19 years.

Due to some possibility of rounding errors in kids’ age, weight, and height, the results you may get from the calculator below may be a little different from other BMI for age percent calculated by other BMI Calculator programs..

Find out if your child is in a healthy BMI range using the calculator below.


Note: Kindly be aware  that this BMI calculator is not meant to serve as a source of clinical guidance and is not intended to be a substitute for professional medical advice. Because BMI is based on weight and height, it is only an indicator of body fatness. Individuals with the same BMI may have different amounts of body fat. Persons may consider seeking advice from their healthcare providers on healthy weight status.

How to Use BMI

The BMI is used as a screening tool for obesity, however the BMI doesn’t diagnose a person’s body fatness or neither does it diagnose the health of a person. In order to determine if the BMI of a person poses a health risk to him or her an health-care provider should be consulted for further assessment and diagnosis.

The assessment can be done to determine the following 1. Skin-fold thickness measurement.  2. Diet Evaluation 3. The physical activities and most importantly the family history

The Current BMI trends for adults in the United States

The current BMI trends for adults in the United States is greater than or equals 30 kg/m (of obsess Status) has increased tremendously since the 70s. However, the good news is that these very trends had levelled off, except for older women of 60 years and above. An obesity trend has been increasing exponentially among women of over 60 years older.

To get more information about the trends of adult obesity in the United States, please check out the  Adult Obesity Facts

Why is the BMI used in the measurement of overweight and obesity?

The BMI is used to measure overweight and obesity because the BMI calculation requires just only height and weight. Secondly, the BMI is not expensive and a very easy tool. To get more information about the formula based on either kilograms and meters or pounds and inches, visit How is BMI calculated?

BMI Calculator How to – What is BMI Formula?

So let us see the most commonly used BMI formula as well how the BMI is calculated. The Body Mass Index (BMI) for both the adult and also the children are basically calculated the same way based on the BMI formula as follows:

The BMI Measurement UnitsThe BMI Formula and Calculation
 Kilograms and meters (or centimetres)BMI Formula are: weight (kg) / [height (m)]2Using the metric system, the BMI formula is weight in kilograms divided by height in meters squared. This is because the height is commonly measured in centimetres, divide height in centimetres by 100 to obtain height in meters.For Example: Weight = 58 kg, Height = 155 cm (1.55 m)Calculation: 58 ÷ (1.55) 2  = 24)
 Pounds and inchesBMI Formula is: weight (lb) / [height (in)]2 x 703To Calculate the BMI: it will be BMI dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703. For Example: Weight = 150 lbs, Height = 5’4″ (58″)Calculation: [115 ÷ (58) 2] x 703 = 24

The BMI interpretation for adults

As for any adult who is above 20 years old, BMI is usually interpreted by using the standard weight designation classes. These classes are of the same categories for men and women of any kind of body 

and ages.These very standard weight designation classes is in correlative with the BMI ranges for adults that are shown in the table below

BMIWeight Designation or Status
17.4- 18.5 belowClassify as Underweight
18.6 – 24.9Classified as Normal or Healthy Weight
25.0 – 29.9Classify as Overweight
30. and AboveClassify as Obese

Let us take a simple example; the figure below represents the weight ranges, their corresponding BMI ranges, as well as their weight designation classes for an adult person who is 5′ 8.

The HeightThe Weight RangeThe BMIThe Weight Designation
5′ 8″125 lbs and less18.4 belowClassify as Underweight
126 lbs and 167 lbs18.5 and 24.9Classify as Normal or Healthy Weight
168 lbs and  201 lbs25.0 and 29.9Classify as Overweight
202 lbs and more30 and higherClassify as Obese

The BMI interpretation for younger children and teenager depend basically upon their ages and sex

How Does BMI interpretation in adults Differ from Children’s BMI interpretation?.

The BMI  interpretation for younger children and adults are done in different ways, even though the BMI for adults and BMI for children uses the same formula for calculation, their interpretations are still different from each other.

The BMI for younger children and teenagers are mainly age and sex-specific, this is because the quantity of fat in the body of children changes with their age and also the quantity of fat in them differ between their sex i.e boys or girl

The Center for disease control CDC BMI for children age growth charts seriously took into account most of the differences as well as visually shown BMI as a percentage ranking.

These percentages were mainly determined by using some specific collated data of the United State of America’s population of between 2 to 20 years old data that was collected from different documented surveys ranging from 1963 to 1965 and 1988 to 1994

The Obesity in children and teens between the ages of 2 years amd 19 years old is defined by the Centre for Disease Control CDC as  BMI above 95 percent of young children and teneegers of about the sex and age in the 1963 -1994 population data that was used as refernce

A good example is a 11 years old child of an average height of 55 inches and weighs 101 pounds would probably have an average BMI of 22,8kg/m. Such BMI would place the boy in the 95 percentage for BMI..

This will mean that such a child has a BMI greater 95 percent when compared to another boy of the same age in the reference population, and as the boy with BMI greater than 95 percent will be considered to have obesity. Check out the CDC Growth Charts for detailed information

You can also check out for more information on the interpreting adult BMI as it doesn’t depend on age or sex

Is The BMI a Good Indicator of Body Fatness?

There is a relatively fairly strong correlation between the Body Mass Index BMI and the body fatness however, studies have shown that two persons may have the same BMI but their level and degree of fatness will surely be different. For example,

  • At the very same BMI, a woman will have more and excess body fat than a man.
  • At the very same BMI, the Blacks people tend to have less body fat than the Whites  also the coloured Asians tend  to have more body fat than do Whites.
  • At the very same BMI, the older persons, on the average, tend to have even more body fat than the younger adults.
  • At the very same BMI, the athletes also tend to have less body fat than do non-athletes persons.

The BMI accuracy is a good indicator of the presence of body fatness; this also shows that body fat is higher in persons who have high BMI. So by implication a person with very BMI for instance 36 kg/m2 will be most likely to have to possess high body fat.

In summary, a high or low BMI can be attributed to body fatness or body leanness. Its is highly recommended you should see a trained health expert or practitioner for better health assessment in other to get an accurate evaluation of your health status

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