How Body Fat Percentage is Calculated
US Navy Method
The Navy method uses simple circumference measurements and is accurate to within 1–3% of DEXA scan results for most people. The formulas differ by sex:
Men: %BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
BMI (Deurenberg) Method
The Deurenberg formula estimates body fat from BMI, age, and sex. It's less accurate than the Navy method but requires only weight, height, and age.
%BF = 1.20 × BMI + 0.23 × age − 10.8 × (1 if male, else 0) − 5.4
Body Fat Categories
Categories follow the American Council on Exercise (ACE) guidelines. Essential fat is required for bodily functions; athletic ranges are typical of competitive athletes; fitness indicates a lean physique; average is health-neutral; obese indicates elevated health risk.