#5 Supplement 1: Converting BMI to bodyfat percent To calcuate BMI, all you need is height and weight. If you're using kilograms and meters, just take your weight in kilograms and divide it by your height in meters squared. So the formula is: (kilos) / (meters x meters). If you're using pounds and inches, you add the northern Virginia area code as a correction factor. The equation is: (703 x pounds) / (inches x inches). Both formulas will give you the same number. Same enough. Almost identical. Then you can look up BMI charts to see where you reside (underweight, normal weight, overweight, obese, larger than that, etc.), compare yourself to age-related norms, and decide if you like your station. Before assigning too much importance to the BMI, it is important to note that it is not a bodyfat percentage. The two numbers are fairly well correlated (just like wealth and lifespan), but they're not the same thing (just like wealth and lifespan). For adults, a BMI under 18.5 is considered underweight; a value between 18.5 and 24.9 is normal; 25-29.9 is overweight; above that trespasses into the stages of obesity (stage I, stage II, etc.). "Obese" doesn't mean you have a high bodyfat percentage though. Bodybuilders are notorious for affixing obese BMIs to lean bodies. So how do you figure out your body composition from your BMI? Well, you don't, really. Bodybuilders and other muscly folk will still look bad. But you can come up with mediocre estimations for the average person. And that calculation requires a bit more information than simple height and weight. You will need the following: BMI, age, sex (male or female), and race (white, African American, or Asian). Okay, here is the formula that converts BMI to an unreliable estimation of BF%: %BF= 63.7 - [1/BMI] - (12.1 x sex) + (0.12 x age) + [129 x Asian x (1/BMI)] - (0.091 x Asian x age) - (0.030 x African American x age). For sex, plug in 0 for female and 1 for male. In the "Asian" part, if you're not Asian, put 0; if you are, put 1. Same with the African American section (0 for no, 1 for yes). For age, it's in years. If you're 42, put 42. For BMI, notice it's not simply BMI, but 1/BMI, so it requires a tiny bit more button-pushing on the calculator. That's it. You'll get a number. And that number will claim to be your bodyfat percentage, and it will do a decent job as a stunt double. Its features are a little off here and there, but it sort of looks like you.