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Calculate Your Body Mass Index - BMI Calculator

Calculate Your Body Mass Index - BMI Calculator

Calculate your BMI
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What is Body Mass Index (BMI)?

Body Mass Index, abbreviated as BMI, is a measure that indicates the ratio of a person‘s weight in kilograms to the square of their height in meters. It is usually expressed in the unit: kg/m2. Body Mass Index is an indicator of body fat and body shape of a person, and high or low BMIs can be an indication of high body fat or low body fat. BMI is an important health indicator for children and adults alike.

Significance of BMI- Meaning of BMI Index

BMI is an indicator of a person‘s body weight with respect to their height and is a single measure of a person‘s body fat levels. As a result, it plays an important role in indicating the body fitness and the amount of fat in a person‘s body.

BMI helps to assess the health risk of a person with respect to their body fat levels. For example, a high BMI indicates that a person‘s body has high fat levels, which means they have health risks associated with high fat levels in the body such as Coronary Heart Diseases (CHDs), Diabetes, High Blood Pressure, High Cholesterol levels in the body etc

Similarly, a low BMI indicates that the person has low body fat with respect to their height which can be associated with a variety of other body conditions such as malnutrition etc.

A BMI is a single convenient factor that can be calculated easily with two easily available figures, i.e. the weight and the height of a person. It is a quick to use and easy to compare figure useful for medical checkups.

So, knowing your BMI as well as its meaning, i.e. whether it is high or low, can help you make a quick and accurate judgment about your body fitness.

Limitations of BMI as a Measure of Health

As an indicator, the BMI is not completely void of limitations and has its own shortcomings as well.

For example, the BMI is overly simplistic in that it solely depends on two factors- weight and height, and ignores a number of other factors such as:

  • The muscle concentration in the body of the person
  • Gender, for e.g. body fat levels are normally higher for women than men
  • The health condition of the person, e.g. pregnancy etc

Based on a number of such factors, it can be said BMI does not give a completely accurate representation of the body fitness and fat levels in the body of a person.

Another important limitation of BMI as an indicator of body fat and fitness levels is that it is based on the assumption that a lower body weight equals fitness, which may not be true as:

  • Some people may have other adverse body conditions which may be detrimental to body fitness despite a normal body weight.
  • Some people may have genetic conditions leading to a greater body weight but are otherwise completely fit and healthy.
  • The body fat levels may fluctuate in case of growing children and aged people.
  • In the case of athletes, the BMI may be high but it does not equate with an unfit body since their muscle concentration is often high.

So, the BMI may not be the best indicator of body fitness and health for a number of cases such as growing children and teenagers, older populations, athletes, pregnant women etc.

How to Calculate BMI?

The calculation of one‘s BMI is really easy, all you need is 2 figures:

  1. Body weight
  2. Height

BMI is expressed in the unit kg/m2 which means that you need to convert your body weight into kilograms and height into meters.

Here we have listed some of the common conversions for you to easily convert your body weight and height into the needed figures:

1 pound = 0.453 kgs

’x‘ pounds = x*0.453 kgs

1 ft = 0.304 m

’x‘ ft = x*0.304 m

1 inch = 0.025 m

1 cm = 0.01 m

“x” cm= x*0.01 m

After you have converted your weight to kgs and height to meters, use the following easy formula to calculate your BMI:

BMI = Weight (kg) ÷ (Height in Meter)2

Using this formula you will be able to calculate your BMI in the kg/m2 unit. Or you can use our free BMI calculator that will help you find out your BMI by just feeding your weight in kg and height in cms.

BMI for Adults

The BMI range of adults (above age 20) on an average basis, irrespective of sex is given here:

BMI Range (In kg/m2)Interpretation
Less than 18.50 (i.e. <=18.50)Less than 18.50 (i.e. <=18.50)Underweight
18.50 - 24.99Normal Healthy Weight Range
24.99 - 29.99Overweight
Above 30 (i.e. >30)Obese

It is to be noted that the above figures are based on data irrespective of gender, age above 20 years, nationality, ethnicity etc. The above values provide a rough idea for the BMI ranges for undrrweight, normal, overweight and obese categories.

BMI for Children

For the calculation of BMI for children and teenagers/adolescents, the process involves the use of age-relevant norms that allow comparison of a child‘s BMI with those of others the same age. This is so because in the case of children, there are other important factors that affect the changes of weight and height:

  • Different children have different fat concentrations and metabolism.
  • There are differences in growth rates of children with respect to age (both for height and weight) which means that the BMI ranges in different ages would vary.
  • The growth rates and the fat concentration of bodies is also different in the case of growing girls and boys.

Keeping all such factors in mind, the calculation of BMI for children and adolescents are calculated by taking their age and gender into consideration as well as plotting a BMI Percentile Chart which shows the percentage of children who fall into the various BMI categories on the basis of their ages .

By doing this, we are not simply calculating the BMI of a child or teen by using their weight and height but also comparing it to others of their age and gender to form a nuanced idea about if their BMI is higher or lower in comparison with others.

Given below are the BMI Percentile comparison categories for children and teenagers aged 2 years to 20 years.

BMI Percentile RangeInterpretation
Below 5th Percentile (i.e. <=5th Percentile)Underweight
5th to 85th PercentileNormal Weight Range
85th to 95th Percentile Overweight
Above 95th PercentileObese

The BMI ranges within each of these percentile categories mentioned above vary depending on the age of the child/teenager.

Body Mass Index Table

Here we have provided you with the BMI tables for adults.

To use the table, find the appropriate height in the left-hand column labeled Height. Move across to a given weight (in pounds). The number at the top of the column is the BMI at that height and weight.

NOTE: All the given figures of BMI are in pounds/inches2 units.

Body Mass Index Table 1
Body Mass Index Table 2
FAQs on The BMI (Body Mass Index) Calculator

You can calculate your BMI by using the formula:

BMI = Weight (kg) ÷ (Height in Meter)2

If you are an adult above 20 years of age, then the healthy BMI range for your age will be between 18.50 - 24.99 kg/m2. In case you are a teenager or child aged between 2 years to 20 years of age, then your correct BMI range would be within the 5th to 85th percentile.

For a person weighing 70 kg with a height of 170 cm (on an average), the BMI will be 24.22 kg/m2.

The normal BMI range for an adult female ranges between 18.50 kg/m2 to 24.99 kg/m2.

The meaning of BMI is an indication of the person‘s body weight with respect to their height. It stands for Body Mass Index (BMI) and is the ratio of body weight (in kg) to the square of height (in meters).

For an adult, a BMI in the range of 24.99 kg/m2 to 25.99 kg/m2 is in the overweight category.

The normal BMI for an adult is in the range of 18.50 kg/m2 to 24.99 kg/m2

For a 10 year-old boy the normal BMI range is 14.2 to 19.4 kg/m2 and for a 10 year old girl the normal BMI range is between 14 to 19.5 kg/m2

For calculating BMI using kg and cms, first convert the height in cms to meters by dividing it by 100. Then you can use the formula for calculation of BMI which is as follows:

BMI = Weight (kg)÷(Height in Meter)2
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