How to Calculate Your Ideal Body Fat Percentage

by E.C. LaMeaux

Body fat percentage is the percentage of your weight that is made up of fat. It consists of both storage body fat and essential body fat. There are several ways to calculate your body fat percentage, including bioelectrical impedance analysis, skin-fold methods and other anthropometric methods, or methods involving the circumference of various body parts. Here’s a method to calculate your body fat using only your scale and a calculator.

Step 1: Know the recommended body fat percentile ranges

First, you must consider variables such as body type, heredity, age, activity and gender. For instance, the range for a healthy body fat percentage in women tends to be higher than that of men, as women need more body fat. A certain amount of fat is important for bodily functions. It regulates your body temperature, cushions organs and tissues, and is the main form of your body’s energy storage. So it’s important to have neither too much nor too little body fat. Mayo Clinic staff, as well as other health professionals, list the following age-adjusted body fat percentile recommendations:


  • 20-40 yrs old: Underfat: under 21 percent, Healthy: 21-33 percent, Overweight: 33-39 percent, Obese: Over 39 percent
  • 41-60 yrs old: Underfat: under 23 percent, Healthy: 23-35 percent, Overweight : 35-40 percent Obese: over 40 percent
  • 61-79 yrs old: Underfat: under 24 percent, Healthy: 36-42 percent, Overweight: 36-42 percent, Obese: over 42 percent


  • 20-40 yrs old: Underfat: under 8 percent, Healthy: 8-19 percent, Overweight: 19-25 percent, Obese: over 25 percent
  • 41-60 yrs old: Underfat: under 11 percent, Healthy: 11-22 percent, Overweight: 22-27 percent, Obese: over 27 percent
  • 61-79 yrs old: Underfat: under 13 percent, Healthy: 13-25 percent, Overweight: 25-30 percent, Obese: over 30 percent

Step 2: Weigh yourself

Obtain as accurate a body weight as possible. Different scales often give different numbers, and depending on the time of day you weigh yourself, your numbers may vary. Try weighing yourself on the same scale at approximately the same time of day over a few days to get an average of your body weight.

Step 3: Calculate your body mass index (BMI)

You can easily calculate your BMI by dividing your weight in pounds by your height in inches squared, and then multiplying by a conversion factor of 703. Using the example of a 150-pound person who is five feet five inches (or 65 inches), the calculation would look like this: [150 ÷ (65)²] x 703 = 24.96

Step 4: Calculate your body fat percentage

According to a study published in the British Journal of Nutrition in 1991, if you are an adult, your percentage of body fat can be estimated as accurately as with skin-fold measurements and bioelectrical tests using the following gender-based formulas in conjunction with your BMI. This calculation has been shown to slightly overestimate body fat percentage in people who are very overweight. Take your BMI result from Step 3 and plug it into the appropriate formula below to calculate your body fat percentage.


  • (1.20 x BMI) + (0.23 x Age) – 5.4 = Body Fat Percentage


  • (1.20 x BMI) + (0.23 x Age) – 16.2 = Body Fat Percentage

Step 5: Compare your body fat percentage to the percentiles listed in Step 1

Take a moment to compare the result you got in Step 4 to the body fat percentiles in Step 1. Comparing your results with these numbers should give you a good indication of how close or how far you may be from your ideal body fat percentage.