What is BMI (Body Mass Index) and How Can I Calculate It?

What is BMI (Body Mass Index) and How Can I Calculate It?


You may have heard the term BMI, which means body mass index, in places like the gym or at a doctor’s appointment.

Body mass index is a measure that uses your height and weight to work out whether your weight is healthy.

In this article, you can find the answers to how to calculate body mass index, the formula for BMI and its limitations, along with a BMI calculator that you can easily use to calculate your own body mass index.



How do I calculate BMI (Body Mass Index)? 

Although BMI is not the only way of calculating your ideal body weight, it can give you a general insight into your physical condition. Height and weight are taken into consideration when calculating your body mass index.



Body Mass Index Formula

The body mass index formula is kg/m2, where kg is your weight in kilograms and m2 is your height in meters squared. BMI helps to find your weight category, but it doesn’t determine your overall fitness and health level.

BMI categories are as follows:

  • Underweight = <18.5
  • Normal weight = 18.5–24.9
  • Overweight = 25–29.9
  • Obese = BMI of 30+

Here’s a body mass index chart for you to find out yours without the BMI formula:

Body mass index chart
Body mass index chart


What’s the problem with BMI?

Your BMI (body mass index), which is calculated based on your weight and height, doesn’t tell you your ideal body weight.

And given that BMI isn’t a perfect measurement for health, calculating your ideal body weight is more important than calculating your BMI. 

For instance, two individuals with the same height and weight – in other words with the same BMI – may look completely different. This is because there are other physiological variables. Every individual has a unique body composition, and their healthy, ideal body weight may vary as a result.

For example, think about a professional athlete who has little body fat, but who has a high BMI because they have a lot of muscle mass, and muscle is heavier, kilo for kilo, than fat. In this case, having a high BMI doesn’t mean they are overweight.



To sum up

BMI is a very simple measurement. While it takes height and weight into consideration, it doesn’t include factors such as:

  • gender
  • waist or hip measurements
  • proportion or distribution of fat
  • proportion of muscle mass

These factors have an important impact on health and how your body looks.

So calculating your ideal body weight using that specific formula is a much more accurate method of determining whether you need to take action about your weight.

Therefore, important decisions about health and nutrition should not be made solely on the basis of body mass index results.

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