Body Fat Percentage Calculator
Estimate your body fat percentage using the US Navy circumference method.
The scale weight alone doesn't tell you whether you're gaining muscle or losing fat. Body fat percentage is the more informative number. The US Navy method uses tape measurements and is accurate to within 3–4% of DEXA scan results for most people, good enough for tracking trends over weeks and months.
The US Navy method is accurate to ±3–4% compared to DEXA scan for most people. Measure consistently, same time of day, same technique, and track the trend rather than fixating on a single measurement.
How the US Navy method works
The formula uses circumference measurements to estimate body fat. For men: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. For women: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. The method was developed by Hodgdon and Beckett (1984) and validated across military populations. It's the standard body composition screening method used by the US military.
Body fat categories
For men: Essential fat (3–5%), Athletic (6–13%), Fitness (14–17%), Average (18–24%), Obese (25%+). For women: Essential fat (10–13%), Athletic (14–20%), Fitness (21–24%), Average (25–31%), Obese (32%+). Essential fat is the minimum required for physiological function.
Measuring correctly
Waist: measure at the navel level at the end of normal exhalation, don't suck in. Neck: measure just below the larynx, sloping slightly downward at the front. Hip (women only): measure at the widest point of the hips and buttocks. Use a flexible tape pulled snug but not compressing skin. Morning measurements before eating are most consistent.
Frequently asked questions
How accurate is this vs DEXA?
The Navy method typically comes within 3–4% of DEXA for most people in the normal body fat range. It tends to overestimate in very lean individuals. For tracking progress, consistency matters more than absolute accuracy.
What body fat percentage should I target?
Goals vary by purpose. Most general health guidelines suggest men maintain below 20–22% and women below 28–32% for reduced metabolic risk. Athletic ranges are lower. Consult a healthcare provider for personalized targets.