What Are BMI Variables?

Calculating your BMI helps you determine if you're overweight.

Calculating your BMI helps you determine if you're overweight.

If you spend considerable time pacing between the bathroom scale and the full-length mirror in your bedroom, you're likely concerned about your weight. Many people who wonder if they need to gain or lose a few pounds rely on the body mass index, or BMI. Although it's not without controversy, the BMI is used as a way to determine if a person is underweight, a healthy weight, overweight or obese.

Body Mass Index

The body mass index, which dates back more than two centuries, has historically helped people determine an ideal weight for their height. It helps people figure if they're too skinny, too fat or just right. Calculating your own body mass index by doing simple mathematics is outdated. Numerous websites and even smartphone apps can do the work for you. All you need to do is enter the two variables that make up the equation.


Your height is one of the two variables needed to determine your body mass index. Regardless of the measurements you use to calculate your height, typical online BMI calculators require you to input your height in feet and inches, as is the convention in North America. Stand against a wall and have a friend or family member measure your height with a tape measure.


The other variable to help you determine your body mass index is your weight. Once you've entered your height into a BMI calculator, input the number of pounds you weigh. When weighing yourself, do so without shoes or clothing to get an accurate number.


Many health experts consider the body mass index irrelevant in modern-day society for a variety of reasons. Because the calculation does not consider the weights of bone and muscle versus the weight of fat, it can provide some inaccurate results. For example, bodybuilder Arnold Schwarzenegger stood six-foot-two and weighed 235 pounds when competing. According to the equation, Schwarzenegger would have been obese at that time because he had a BMI of 30.2.

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About the Author

Toronto-based journalist William McCoy has been writing since 1997, specializing in topics such as sports, nutrition and health. He serves as the Studio's sports and recreation section expert. McCoy is a journalism graduate of Ryerson University.

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