How to calculate BMI?

BMI, or Body Mass Index, is a number that contextualizes a person's weight and height, indicating whether one’s weight is appropriate for their height.

Computer

If you want to calculate your BMI, use this calculator. The calculation process is explained below. Enter your height in cm and your weight in kg.

How to calculate BMI

Calculating BMI is relatively simple. Take your weight in kilograms and divide it by the square of your height in meters. For example:

The author of this article weighs 74 kg (well, he doesn't—he'd rather weigh himself) and is 177 cm tall. Let's convert the height to meters: 177 cm equals 1.77 meters. We need to square the height, so we need to calculate

$$1{,}77^2=1{,}77\cdot1{,}77=3{,}1329$$

Now we take the weight in kilograms and divide it by our result, which is 3.1329:

$$BMI=\frac{74}{3{,}1329}=23{,}62$$

The resulting BMI of the article's author is thus 23.62 (and the author has lost a significant amount of weight). The complete formula is as follows:

$$\LARGE\mbox{BMI}=\frac{\mbox{kg}}{\mbox{m}\cdot\mbox{m}}$$

where kg is your weight in kilograms and m is your height in meters.

How to read the resulting BMI

Using the calculated BMI value, we can determine in just a few minutes whether a person is overweight, underweight, or has a healthy weight. However, BMI is not a very accurate indicator; it does not consider many other factors, such as distinguishing between fat and muscle. By only taking into account height and weight, it remains a very approximate measure. Commonly, BMI values are interpreted as follows:

• BMI below 18.5: a person is considered underweight,
• BMI between 18.5 and 25: Normal weight,
• BMI between 25 and 30: Overweight,
• BMI above 30: Obese.