How to Calculate Body Fat With a Tape Measure

When measuring body fat percentages, it's important to know that gender and age both play a big part in determining a healthy percentage. For example, a body fat percentage between 19 percent and 26 percent is considered good in females in their 20s and 30s. For females over 40, 23 percent to 30 percent is good. With men, a body fat percentage between 10 percent and 20 percent is considered good for males in their 20s and 30s, and a percentage of 19 percent to 23 percent is good with men over 40.

Instructions

Calculating Male Body Fat

• 1

  Step onto your scale and take note of your body weight. For example, use 190 pounds.

• 2

  Measure the size of your waist with your tape measure, in inches. For example, use 30.5 inches.

• 3

  Multiply your total body weight by 1.082. Using the example numbers, this means 190 x 1.082 = 205.58. Next, take that result and add it to 94.42. Call this Result 1. Using the example numbers, this means 205.58 + 94.42 = 300.

• 4

  Multiply your waist size by 4.15. Using the example numbers, this means 30.5 x 4.15 = 126.575. Call this Result 2. Take Result 1 and subtract Result 2 from it. Using the example numbers, this means 300 - 126.575 = 173.425. This number represents your lean body weight.

• 5

  Subtract your lean body weight from your total body weight. Using the example numbers, this means 190 - 173.425 = 16.575. Take this result and multiply it by 100. Using the example numbers, this means 16.575 x 100 = 1,657.5. Now, take this result and divide it by your total body weight. Using the example numbers, this means 1,657.5 / 190 = 8.72. This number is your percentage of body fat. Therefore, using the example numbers, this person has 8.72 percent body fat.

Calculating Female Body Fat

• 6

  Step onto your scale and take note of your body weight. For example, use 125 pounds.

• 7

  Measure the size of your wrist with your tape measure, in inches. For example, use 6 inches.

• 8

  Measure the size of your waist with your tape measure, in inches. For example, use 24 inches.

• 9

  Measure the size of your hips with your tape measure, in inches. You should measure your hips at the widest point. For example, use 38 inches.

• 10

  Measure the size of your forearm with your tape measure, in inches. You should measure your forearm at its widest point. For example, use 9.5 inches.

• 11

  Multiply your total body weight by 0.732. Using the example numbers, this means 125 x 0.732 = 91.5. Call this Result 1.

• 12

  Add 8.987 to Result 1 and call this Result 2. Using the example numbers, this means 8.987 + 91.5 = 100.487.

• 13

  Divide your wrist circumference by 3.14 and call this Result 3. Using the example numbers, this means 6 / 3.14 = 1.91.

• 14

  Multiply your waist measurement by 0.157 and call this Result 4. Using the example numbers, this means 24 x 0.157 = 3.768.

• 15

  Multiply your hip measurement by 0.249 and call this Result 5. Using the example numbers, this means 38 x 0.249 = 9.462.

• 16

  Multiply your forearm measurement by 0.434 and call this Result 6. Using the example numbers, this means 9.5 x 0.434 = 4.123.

• 17

  Add Result 2 to Result 3 and call this Result 7. Using the example numbers, this means 100.487 + 1.91 = 102.397.

• 18

  Subtract Result 4 from Result 7 and call this Result 8. Using the example numbers, this means 102.397 - 3.768 = 98.629.

• 19

  Subtract Result 5 from Result 8 and call this Result 9. Using the example numbers, this means 98.629 - 9.462 = 89.167.

• 20

  Add Result 6 to Result 9. This number will represent your lean body mass. Using the example numbers, this means 4.123 + 89.167 = 93.29.

• 21

  Subtract your lean body mass from your total body weight. Using the example numbers, this means 125 - 93.29 = 31.71. Next, take this number and multiply it by 100. Using the example numbers, this means 31.71 x 100 = 3,171. Now, take this number and divide it by your total body weight. Using the example numbers, this means 3,171 / 125 = 25.368. Therefore, using the example numbers, this person has 25.268 percent body fat.