Body Fat Percentage Calculator
About Body Fat Percentage Calculator
Understanding Body Fat Percentage
Body fat percentage is the proportion of your total body mass that consists of fat tissue. Unlike BMI, which only considers height and weight, body fat percentage distinguishes between fat mass and lean mass (muscle, bone, organs, water). Two people can have identical BMI scores but vastly different body fat levels. An athletic 200-pound man at 12% body fat is in excellent shape, while a sedentary 200-pound man at 30% body fat faces significant health risks. Knowing your body fat percentage gives you a much clearer picture of your fitness level.
The US Navy Method
This calculator uses the US Navy circumference method, which estimates body fat from measurements of the neck, waist, and hips (for women). The formula for men is: %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. For women: %BF = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387. This method correlates well with hydrostatic weighing (accuracy within 3-4%) and requires only a tape measure.
Body Fat Categories
For men: Essential fat 2-5%, Athletes 6-13%, Fitness 14-17%, Average 18-24%, Obese 25%+. For women: Essential fat 10-13%, Athletes 14-20%, Fitness 21-24%, Average 25-31%, Obese 32%+. Women naturally carry more essential fat for reproductive health. Going below essential fat levels is dangerous and impairs normal body function.
Frequently Asked Questions
How accurate is the Navy method?
The Navy method is accurate within 3-4% for most people when measurements are taken correctly. It is less accurate for very lean or very obese individuals. DEXA scans provide the gold standard measurement.
What is a healthy body fat percentage?
For men, 10-20% is generally healthy. For women, 18-28% is healthy. Athletes typically maintain lower levels, but extremely low body fat has health consequences including hormonal disruption.
How should I take measurements?
Measure neck at the narrowest point below the larynx. Measure waist at the navel level. Measure hips (women) at the widest point. Take measurements in the morning on bare skin. Use a flexible tape measure without compressing the skin.
