How to Calculate a BMI Using Measurements
Overview
According to the National Institutes of Health (NIH), BMI, or body mass index, is an estimate of body fat for adults based on height and weight. There are several BMI calculators available online, but you can perform the calculation on your own. If you know your current height and weight you can use those measurements to calculate your BMI. The equation for BMI does require weight in kilograms and height in meters, but if your measurements are in pounds and inches it is easy to convert these numbers.
Step 1
Determine your weight in kilograms. Divide your weight in pounds by 2.2 to convert it to kilograms. For example, if you weigh 170 pounds, your weight would be 77.27 kilograms.
Step 2
Determine your height in meters. Multiply your height in inches by 2.54 to determine centimeters. Divide this number by 100 to get meters. For example, if your height is 66 inches, your height is 1.68 m.
Step 3
Square your height. Do this by multiplying the number by itself. For example, 1.68 meters would be 2.82 meters squared.
Step 4
Divide your weight in kilograms by your height in meters, squared. For this example, the equation would be 77.27 kilograms divided by 2.82 meters squared, or 27.4.
Step 5
Consider the number you get for this final calculation your BMI.
Tips and Warnings
- The BMI is classified into four categories. A BMI of less than 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight and 30 or greater is obesity.
- While the BMI is considered a reliable indicator of body fat for most populations, the NIH states that it may overestimate body fat in athletes with large muscle mass and underestimate it in older persons with less muscle mass.
About this Author
Lori Rice is a freelance health and travel writer. With a Master’s degree in Nutritional Sciences and a Bachelor’s degree in Nutrition, Fitness and Health, she strives to positively influence the wellness of her readers. As an avid traveler and current ex-pat she enjoys sharing her experiences and tips with other enthusiastic explorers.
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