Requires waist and neck measurements
Enter your measurements and click Calculate Body Fat to see your results
Developed by the U.S. Navy for fitness assessments. Uses neck, waist (and hip for women) circumference with height to estimate body fat via a logarithmic formula. Accurate to within ±3–4% of DEXA scans.
BMI doesn't distinguish between fat and muscle. A bodybuilder might have a "high" BMI but low body fat. Body fat % gives a much more accurate picture of actual health and fitness status.
Measure in the morning before eating. Stand relaxed, don't suck in your gut. Waist at navel level. Neck below Adam's apple. Hips at widest point. Use a flexible tape measure.
Women naturally carry 6–11% more body fat than men due to essential fat needed for reproductive function. This is why body fat categories differ significantly between genders.
Your body fat percentage is one of the most important indicators of physical health and fitness level. While BMI provides a rough screening tool based on height and weight alone, body fat percentage tells you exactly how much of your body weight is composed of fat tissue versus lean mass (muscle, bone, water, organs). This body fat calculator uses the U.S. Navy Method — a validated circumference-based estimation technique that requires only a measuring tape and your basic measurements.
The U.S. Navy developed this formula for military fitness assessments because it needed a reliable, equipment-free method to evaluate body composition across large groups. For men, the formula uses height, waist circumference (measured at the navel), and neck circumference: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. For women, the hip circumference is added: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. All measurements should be in centimeters for the metric version. Research has validated this method to be within ±3–4% of DEXA scan results.
Essential fat (2–5% men, 10–13% women) is the minimum required for basic physiological function — dropping below this level is dangerous. Athletes (6–13% men, 14–20% women) maintain very low fat while preserving performance. The fitness range (14–17% men, 21–24% women) represents a lean, healthy physique. Average body fat (18–24% men, 25–31% women) is typical and considered acceptable, while obese levels (25%+ men, 32%+ women) are associated with increased health risks including cardiovascular disease, Type 2 diabetes, and joint problems.
BMI and body fat percentage measure fundamentally different things. A muscular athlete with visible abs might have a BMI of 28 ("overweight") but only 12% body fat. Conversely, someone with a "normal" BMI of 23 could carry 30% body fat if they have very little muscle mass — a condition sometimes called "skinny fat" or normal-weight obesity. Using both metrics together provides the most comprehensive picture of your health status.
Healthy fat loss involves maintaining a moderate caloric deficit (300–500 calories below TDEE) while consuming adequate protein (1.6–2.2g per kg body weight) and engaging in resistance training to preserve lean mass. Aim to lose 0.5–1% of body weight per week. Crash diets and extreme deficits lead to muscle loss and metabolic adaptation, which makes long-term fat loss harder. Monitor your body fat percentage every 4–6 weeks to track progress rather than relying solely on scale weight.
For a complete health assessment, combine this body fat calculator with our BMI Calculator, Lean Body Mass Calculator, and Ideal Weight Calculator.
The U.S. Navy method is accurate to within ±3–4% of DEXA scan results for most people. It's one of the most accessible and reliable circumference-based methods available.
For men: athletes 6–13%, fitness 14–17%, average 18–24%. For women: athletes 14–20%, fitness 21–24%, average 25–31%. Women naturally carry more essential fat for reproductive function.
Measure at the navel (belly button) level while standing relaxed. Don't suck in your stomach. For neck, measure just below the Adam's apple. For hips (women), measure at the widest point of your buttocks.
Body fat percentage gives a more accurate picture since BMI can't distinguish muscle from fat. However, using both together provides the best health assessment.
