The percentage of your body weight that's due to fat is generally a better indicator of your fitness than your total body weight. You may find that your body weight changes little or even increases when you begin a fitness program, because you can gain muscle at the same time that you lose fat. You can estimate your body fat percentage from physical measurements that you take at home.
Step 1
Measure your waist in inches at the level of your navel. Weigh yourself in pounds with a scale. Perform these measurements in the morning when your water weight is at its lowest level.
Step 2
Take additional measurements if you're female. Measure the circumferences of your wrist, forearm and hips in inches. Make these measurements at their fullest points.
Step 3
Calculate your lean body mass with the following formula from Dave Draper if you're male: (Body Weight x 1.082) - (Waist x 4.15) + 94.42.
For an example, let your waist measure 34 in. and your body weight be 166 lbs. You have a lean body mass of (166 x 1.082) - (34 x 4.15) + 94.42 = 133 lbs.
Step 4
Compute your lean body mass with the following formula from Dave Draper if you're female: (Body Weight x 0.732) - (Waist x 0.157) + (Wrist / 3.14) + (Forearm x 0.434) - (Hips x 0.249) + 8.987.
As an example, let your waist measure 31 in. and your body weight be 135 lbs. Your wrist measures 6 in., your forearm measures 9 in. and your hips measure 39 in. You have a lean body mass of (135 x 0.732) - (31 x 0.157) + (6 / 3.14) + (9 x 0.434) - (39 x 0.249) + 8.987 = 99 lbs.
Step 5
Derive your body fat percentage from your lean body mass with the equation: (Body Weight - Lean Body Mass) / (Body Weight) x 100.
As an example, let your body weight be 166 lbs. and your lean body mass be 133 lbs. Your body fat percentage is (166 - 133)/ (166) x 100 = 19.9 percent.
Things You'll Need
- Tape measure
- Scale
- Calculator
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