The amount of body fat you have can be an accurate measure of your physical fitness. You typically express body fat as a percentage of your total body weight, rather than the actual weight of your body fat. You can calculate your body fat at home with a tape measure and bathroom scale. This requires a gender-specific formula to calculate your lean body weight, which you then can convert to your body fat percentage.
Step 1
Take measurements that apply only to females. Measure the circumference of your forearm, wrist and hips at their widest points. Use a tape measure that measures in inches.
Step 2
Make measurements that apply to both genders. Weigh yourself with a scale that uses pounds. Measure the circumference of your waist at the level of your navel with a tape measure that uses inches.
Step 3
Calculate the lean body mass for females. Dave Draper provides an equation for this calculation: weight x 0.732 + forearm x 0.434 + wrist / 3.14 - hips x 0.249 - waist x 0.157 + 8.987. For the example, assume that you weigh 137 pounds. Your forearm measures 9 inches, your wrist measure 6 inches, your hips measure 37 inches and your waist measures 28 inches. Your lean body mass is 137 x 0.732 + 9 x 0.434 + 6 / 3.14 - 37 x 0.249 - 28 x 0.157 + 8.987 = 101 pounds.
Step 4
Compute the lean body mass for males. Dave Draper uses the following equation: body weight x 1.082 - waist x 4.15 + 94.42. Assume you weigh 159 pounds and your waist measures 32 inches. Your lean body mass is 159 x 1.082 - 32 x 4.15 + 94.42 = 134 pounds.
Step 5
Convert your lean body mass to your body fat percentage. This calculation uses the following formula: weight - lean body mass x 100 / weight. Assume your weight is 137 pounds and your lean body mass is 101 pounds. Your body fat percentage is 137 - 101 x 100 / 137 = 26.3 percent.
Things You'll Need
- Tape measure
- Scale
- Calculator
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