You can determine your body fat percentage from your weight and a few body measurements. These measurements will provide your lean body mass, which you'll then convert into your body fat percentage. These formulas will require you to make different measurements depending on your gender. You'll commonly use this procedure to monitor your loss of body fat as you follow a fitness program.
Step 1
Take your measurements with a tape measure that uses inches. Measure your waist at the navel. You'll also need to measure your hips and forearms at their widest points if you're female. Females will also need to measure their wrists at the narrowest point.
Step 2
Weigh yourself with a scale in pounds. Your body fat percentage will be more accurate if you weigh yourself when you wake up, when your water weight is at its lowest level.
Step 3
Compute your lean body weight if you're male. This will use the equation (1.082 x weight) - (4.15 x waist) + 94.42. If you have a 38-inch waist and weigh 189 lb., your lean body weight is (1.082 x 189) - (4.15 x 38) + 94.42 = 141 lb.
Step 4
Derive your lean body weight if you're female. This will use the equation (0.732 x weight) -- (0.157 x waist) -- (0.249 x hips) + (0.434 x forearm) + (wrist measurement / 3.14) + 8.987. Assume you have a 33-inch waist and weigh 143 lb., and you have 37-inch hips, 10-inch forearms and 6-inch wrists. Your lean body weight is (0.732 x 143) -- (0.157 x 33) -- (0.249 x 37) + (0.434 x 10) + (6 / 3.14) + 8.987 = 106 lb.
Step 5
Compute your body fat percentage for both genders. This will use the equation (total body weight - lean body weight) x 100 / (total body weight). Assume you weigh 189 lb. and have a lean weight of 138 lb. Your body fat percentage is (189 - 141) x 100 / 189 = 25.4 percent.
Things You'll Need
- Tape measure
- Scale
- Calculator
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