How to Calculate BMI - With Online BMI Calculator!

January 12, 2020
Est. Reading: 4 minutes

How to lose weight? How to become taller? Everyone is obsessed with their BMI these days. Be it for health purposes or to simply look good for your partner, learning how to calculate BMI is a great way to start knowing that you are not in shape!


What is BMI

Body mass index (BMI) is used to measure the amount of fat percentage in an adult person and is derived from his or her height and weight. 

As a rule of thumb, the BMI (measured in kg/m^2) is used to determine if a person has a suitable weight with the following categorisation: Underweight (Less than 18.5), Normal (18.5 to 23), Overweight (More than 23). 

How to calculate BMI?

Belgian mathematician Lambert Adolphe Jacques Quetelet

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In 1930, Belgian mathematician Lambert Adolphe Jacques Quetelet created the BMI to determine if a person has a healthy weight based on his or her height with the following formula:

BMI = Weight  / (Height * Height) 

For example, a person that has a weight of 70 kg and a height of 1.7m would have a BMI of 70 / (1.7*`1.7) = 24.22. This places that person in the overweight category and he or she should take action in lowering his or her weight.

Note: BMI should not be used to calculate health risks for pregnant women or youth under the age of 18.

weighing maching digital weighing scale

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BMI calculator - Online Tool

What is the BMI used for?

The BMI is used by various health institutions all around the world as a gold standard in assessing if a person’s weight is ideal.

Public Health Statistics

BMI is used to determine the level of obesity within a country. 

For example, the EU uses this to determine the number of obese people within the union and informing the public of the dangers an unhealthy BMI can create. 

In national-wide health screenings, BMI is commonly used to determine if someone has the ideal weight or not.

doctor analysing x-rays of patient bmi

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This important metric is also used to determine if an individual is suitable to become a runway model, whereby the BMI averages around 16. 

However, there has been a backlash for forcing female models to reach dangerously low BMI values as we move towards a more contemporary society which promotes health over fashion in the future.

runaway model dangerously low bmi

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What are the benefits of good BMI?

A healthy BMI provides many benefits. Here are the 2 biggest ones:

Strengthening bones and joints

The right amount of weight on your body puts less stress on bones and joints while ensuring there is enough muscle mass to sustain daily activities. 

Being too light or too heavy may cause difficulties during exercise and risk injury.

Girl keeping fit lifting weights to maintain bmi

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Reducing the risk of health problems

With a healthy fat level in the body, it is less likely that dangerous issues such as high blood pressure or stroke may occur. 

What happens when you have bad BMI?

An unhealthy BMI can cause many health problems and you should not have too high or too low BMI. 

heart problems stroke unhealthy bmi problems

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The following are the different types of health problems commonly associated with being obese:


This occurs when blood cannot flow to the brain properly, resulting in brain damage as it fails to perform properly. Strokes can cause permanent damage and may result in blindness, inability to move or feel and even difficulties in talking or hearing.


Cancer comes from abnormal cell growth which may spread to other parts of the body. This can cause unusual bleeding, weight loss or even changes in bowel movements. In general, cancer occurs in various stages with stage 4 being the most dangerous as the cancerous cells would have already spread from its original position to parts of the body.

Type 2 Diabetes

When you have too much sugar in your blood (also known as blood glucose) which may require you to take insulin. Being a common health problem, type 2 diabetes may lead to various diseases (such as heart or kidney), blindness and even amputation.

High Blood Pressure

Blood is pumped by the heart to all parts of the body through the arteries. Blood pressure is a measure of how strong the blood is being pumped by the heart and blockages in the arteries may cause overall blood pressure to increase. Too high blood pressure may damage the kidneys that regulate it.

measuring high blood pressure for health problems

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Heart Disease

Heart disease usually describes various conditions ranging from blockages in the artery to heart rhythm complications. This is a broad term which has varying symptoms and effects and may lead to serious complications including death.

Learning how to calculate BMI is generally a good checking metric for personal health, but one must not be too fixated on a single factor. 

Having the perfect BMI does not necessarily mean anything good if you do not cultivate good lifestyle habits. These habits can include, but not limited to, a good exercise regime, healthy diet, a good work-life balance and spending quality time with your loved ones. 

We recommend doing a checkup at least once a year too, just to be on the safe side.

So, what are you waiting for? Be a healthier person today!

be a healthier person after measuring calculating how to calculate bmi

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Related to how to calculate BMI:

4 Really Easy Things to DO For A Healthy Lifestyle

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