Formula to Calculate BMI
Overview
BMI stands for Body Mass Index. A BMI calculation is used as a guide to determine if you are underweight, at a normal weight or overweight. Although BMI is generally accurate, it can be misleading. For instance, a bodybuilder will have a high BMI because of his muscle mass, but he is not fat. The formula to calculate BMI is [weight in pounds] / [height in inches squared] x 703.
Step 1
Convert your height into inches. There are 12 inches in each foot. For example, a person who stands 5 feet 9 inches is 69 inches tall (5 x 12 + 9 = 69).
Step 2
Take your height in inches and square it. For example, the squared height calculation for a 5-foot-9 person is 4,761 (69 x 69 = 4,761).
Step 3
Divide your weight by your squared height. For a person who weighs 150 pounds and has a squared height of 4,761, 150 / 4,761 = .0315.
Step 4
Multiply the number from Step 3 by 703 to get your BMI. For example, if you weigh 150 pounds and are 5 feet 9 inches tall, you have a BMI of 22.1 (.0315 x 703 = 22.1).
Tips and Warnings
- The following BMI guidelines for adults are provided by the Centers for Disease Control and Prevention: If your BMI is below 18.5, you are underweight. If your BMI is 18.5 to 24.9, you are at a normal weight. If your BMI is 25.0 to 29.9, you are overweight. If your BMI is 30.0 and higher, you are obese.
References
About this Author
Rose Kivi has been a writer for over 10 years. She has a background in the nursing field, wildlife rehabilitation and habitat conservation. Kivi has authored educational textbooks, patient health care pamphlets, animal husbandry guides, outdoor survival manuals and was a contributing writer for two books in the Uncle John’s Bathroom Reader Series.
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