How to Calculate Percent Body Fat from Waist Girth and Weight

Body Fat Equation for Males

For men, there are many methods of calculating percent body fat and lean body mass based on body measurements. One particularly easy method is to calculate male body fat based on weight and waist circumference. The only tools required are a scale and tape measure. You can apply the formulas below using a hand calculator and your body measurements, or use the convenient body fat calculator on the left.


First, determine your weight in pounds and call this number W. Next, measure the girth of your waist in inches and call this number G. For men, the natural waist is not necessarily the narrowest point on the abdomen. Your lean body mass (in pounds) can be approximated with the formula


LBM = 94.42 + 1.082W - 4.15G



Your total body fat (in pounds) is given by the equation

TBF = W - LBM
= 4.15G - 0.082W - 94.42

And finally, you percent body fat is

%BF = (4.15G - 0.082W - 94.42)/W times 100%

Example: Suppose a man weighs 180 pounds and has a waist girth of 33 inches. Then is lean body mass is computed to be

94.42 + 1.082(180) - 4.15(33) = 152.23 lbs

His total body fat is thus 180 - 152.23 = 27.77 lbs. And finally, his percent body fat is 15.43%, since 180/27.77 = 0.1543.


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