Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method. Enter your gender, height, waist, neck, and hip measurements to get your body fat category.
Understanding Body Fat Percentage
Body fat percentage is the proportion of fat tissue relative to total body weight. Unlike BMI, it directly accounts for body composition, making it a more accurate indicator of fitness level and health risk. The US Navy method, developed by Hodgdon and Beckett at the Naval Health Research Center, is a well-validated approach used by all branches of the US military.
US Navy Body Fat Formula
For men: Body Fat % = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. For women: Body Fat % = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387. All measurements should be in centimeters. Lean body mass is then calculated as: LBM = Total Weight x (1 - Body Fat % / 100).
Body Fat Categories (Men / Women)
- Essential Fat: 2-5% / 10-13% — minimum required for basic physiological function
- Athletic: 6-13% / 14-20% — typical of competitive athletes
- Fitness: 14-17% / 21-24% — active, regularly exercising individuals
- Average: 18-24% / 25-31% — typical for the general population
- Obese: 25%+ / 32%+ — associated with increased health risks
Health Risks by Body Fat Level
- Too low: hormonal imbalances, weakened immune system, bone density loss, fertility issues
- Healthy range: reduced risk of cardiovascular disease, diabetes, and certain cancers
- Too high: increased risk of heart disease, type 2 diabetes, hypertension, sleep apnea, and joint problems
Comparison of Body Fat Measurement Methods
- DEXA scan: gold standard, accurate to 1-2%, costs $50-$150 per session
- Hydrostatic weighing: accurate to 2-3%, requires specialized facility
- US Navy method: accurate to 3-4%, free and easy to do at home
- Bioelectrical impedance (scales): convenient but varies 4-5%, affected by hydration
- Skinfold calipers: 3-4% accuracy, requires trained technician for best results
Measurement Tips
- Measure in the morning before eating or drinking for consistency
- Use a flexible (cloth or plastic) tape measure, not a metal one
- Keep the tape level, horizontal, and snug but not compressing skin
- Take each measurement 2-3 times and use the average for accuracy
- Stand relaxed — do not flex muscles or hold your breath during measurements