The body fat percentage is the total mass of fat divided by total body mass. There are a number of proposed formulas to estimate body fat percentage. We use the formula derived by Deurenberg and co-workers to calculate body fat percentage from body mass index (BMI) in our calculations. Note that the results are just estimates and not accurate figures. See the table below for typical body fat amount specified by the American Council on Exercise (ACE).
Use this calculator to find out the BMI, if you haven't done yet.
Body fat % (Children) = (1.51 × BMI) - (0.70 × Age) - (3.6 × sex) + 1.4
Body fat % (Adults) = (1.20 × BMI) + (0.23 × Age) - (10.8 × sex) − 5.4
where sex is 1 for males and 0 for females.