How to Calculate Percentages of Fat & Muscle

Whatever percentage of our bodies is not fat is comprised of essential muscles, bones and organs.

The body mass index (BMI) is a measurement that allows us to determine what percentage of our body's weight is made up of fat. The percentage of our weight that is not fat is comprised of muscle, bones, organs and blood. When calculating what percentage of the body is fat, it is necessary for men and women to take measurements from different parts of the body. Men and women must also use different formulas for calculating their BMI. Age and bone density are also taken into account when calculating the body's fat percentage.

Things You'll Need

• Body fat calipers
• Calculator

Instructions

For Men

1. Pinch the skin on your chest, halfway between your armpit and your nipple and take a measurement of the skin fold using the body fat calipers. Make a note of this measurement.

2. Vertically pinch the skin 1 inch above your belly button and take a measurement. Write down the measurement.

3. Pinch the skin on your thigh vertically, about halfway between your knee and the top of your thigh. Again, record the caliper reading.

4. Repeat all of the skin-fold measurements two more times, then average the three measurements for each measurement point. Add the three averaged measurements you recorded together and make a note of their sum. In the formulas below, this number will be designated as SUM3.

5. Calculate the appropriate bone density for your age by using the following formula: 1.1093800 - (0.0008267 * SUM3) + (0.0000016 * SUM3²) -(0.0002574 * Age). Then calculate your body fat percentage using the following formula: [(4.95/Bone Density) - 4.5] 100.

For Women

1. Vertically pinch the skin of your tricep, halfway between your shoulder and your elbow. Use the body fat calipers to measure the skin fold and make a note of the measurement. This particular measurement is much easier to get if taken by a buddy.

2. Vertically pinch the skin near the side of your body, just above the place where your hip bone comes forward. Measure the skin fold and record the measurement.

3. Pinch the skin on your thigh vertically, about halfway between your knee and the top of your thigh. Again, record the caliper reading.

4. Repeat all of the skin-fold measurements two more times, then average the three measurements for each measurement point. Add the three averaged measurements you recorded together and make a note of their sum. In the formulas below, this number will be designated as SUM3.

5. Calculate the appropriate bone density for your age by using the following formula: 1.0994921 - (0.0009929 * SUM3) + (0.0000023 * SUM3²) - (0.0001392 * AGE). Then calculate your body fat index using this formula: [(4.95/Bone Density) - 4.5] 100

Tips & Warnings

• Always stand when taking body fat measurements.

• All measurements should be taken on the right side of the body.

• When pinching skin, pinch about a double thickness of your skin. Pinching too deeply will cause you to measure muscle as well as fat.

• You need to pinch the skin folds hard enough to squeeze the water out of them. This means pinching hard enough that it is slightly uncomfortable.

• Body fat calipers should be placed at the halfway point between your body and the top of the skin fold being measured.

References

• The Build Muscle and Gain Weight Fast Guide: How To Take Skinfold Measurements and Calculate Body Fat Percentage
• HealthCheck Systems: Understanding Your Body Fat Percentage