Calculating your body fat percentage, also known as your body mass index, can be done using a standard formula if you're a woman. The most accurate way to measure your body fat percentage, however, is underwater weighing. But a basic formula will give you an idea of your fat percentage once you take several measurements.
Weigh yourself on the scale. Take your body weight in pounds and multiply it by 0.732. Now take your answer and add 8.987 to it. Record your answer on paper.
Measure your wrist at the fullest part. Take the measurement in inches and divide it by 3.14. Write it down.
Measure your waist at your naval. Multiply this measurement by 0.157. Record this measurement
Measure your hips at the fullest point. Multiply this measurement by 0.249. Record the result.
Measure your forearm at the fullest point. Take the measurement and multiply it by 0.434. Jot down the product.
Calculate your lean body mass. To do this, add together answers you recorded in Steps 1 and 2. Take this new answer and subtract the result from Step 3. Take that number and subtract the result from Step 4. Take that answer and add the result from Step 5. This result is your lean body mass.
Calculate your body fat weight. Take your body weight (weight on the scale) and subtract your lean body mass (the answer from Step 6).
Take the result from Step 7 and multiply it by 100. Take this answer and divide it by your total body weight (weight on the scale). This is your body fat percentage.