BMI is not calculated by height alone but is a measure of your mass (weight) divided by your height squared. The calculation is figured in kilograms and meters so you must convert your measurements prior to using the formula.
The ideal BMI for any height ranges between 19 and 25.
Underweight: BMI less than 18.5
Healthy: BMI between 19-25
Overweight: BMI greater than 25.5
Obese: BMI greater than 30
How to Convert to Metrics
Height: In order to convert your height to meters, multiply your height in inches by 0.025. For example, 5-feet 6-inches would be 66 inches. Multiplied by 0.025 the total would be 1.65 meters.
Weight: In order to convert your weight to kilograms, multiply your weight in pounds by 0.45. For example, if you weigh 130lbs multiplied by 0.45 you would weigh 58.5 kilograms.
Using the conversion example above of the 5’6″ woman weighing 130 lbs we would use the following formula:
58.5/1.65² (1.65 x 1.65 =2.72)
Body Mass Index Caveat
Because it is a very simple calculation, the Body Mass Index is commonly used as a health indicator, but does not come without its drawbacks. Dividing your mass by your height is a casual estimation of your body’s percentage of fat. The index will give false readings in a variety of cases such as an athlete with a high proportion of lean muscle or an elderly person that is underweight but may have a high percentage of body fat.
“HOW TO CALCULATE YOUR BODY MASS INDEX OR BMI.” EXTOXNET – The EXtension TOXicology NETwork. N.p., n.d. Web. 30 Mar. 2011. http://extoxnet.orst.edu/faqs/dietcancer/web2/twohowto.html.
“Calculating Your BMI.” NetWellness Homepage. N.p., n.d. Web. 30 Mar. 2011. http://www.netwellness.uc.edu/healthtopics/quality/calculatingbmi.cfm.