How to Calculate Lean Body Mass & Percent Body Fat with Girth Measurements (Women)

There are many techniques for women to estimate their lean body mass and percent body fat. One such method, developed by physiologists in the 1980s, uses girth measurements around the waist, hips, forearm, and wrist. These circumference measurements, along with a woman's weight, are then plugged into special formulas that yield the amount of lean tissue and fat in a female body. The steps below will show you how to take the measurements and apply the equations. You can also try the lean body mass and fat calculator at left.

Wrap a tape measure around your waist at the navel and measure the girth of your waist in inches. Call this number "Wa". You should suck in your gut a little, and keep the tape measure snug, but not too tight.

Find the circumference of your hips at their widest point, and call this number "Hi."

Measure the girth of your forearm at its thickest point (a little below the elbow) and call this number "Fo."

Find the circumference of your wrist, and call this number "Wr." Remember to keep all measurements in inches.

Lastly, on a bathroom scale, find your weight in pounds and call this Number "We."

Next, plug the numbers Wa, Hi, Fo, Wr, and We into this formula to estimate your lean body mass (LBM) in pounds. (Lean body mass is simply the amount of non-fat tissue in your body, i.e., the water, bone and muscle.)

LBM = 8.987 - 0.157Wa - 0.249Hi + 0.434Fo + 0.318Wr + 0.732We

To find your percent lean body mass, simply divide your LBM by your weight.

To find your total body fat, subtract your LMB from your weight, and this is the total weight of fat in your body. To find your percent body fat, simply divide your total fat by your weight.

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