Body Fat Percentage Calculator
Estimate your body fat percentage using the US Navy circumference method — no calipers or DEXA needed.
Body Fat % Calculator
US Navy Method
The US Navy method uses neck, waist (and hip for women) circumferences to estimate body fat. It's the same method used by military branches for fitness testing — practical and reasonably accurate without any expensive equipment.
Formula (men): 86.01 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76. Women also factors in hip measurement.
Body Fat Percentage Classifications
| Category | Men | Women |
|---|---|---|
| Essential Fat | 3 – 5% | 10 – 13% |
| Athletic | 6 – 13% | 14 – 20% |
| Fit | 14 – 17% | 21 – 24% |
| Average | 18 – 24% | 25 – 31% |
| Obese | 25%+ | 32%+ |
Understanding Body Fat Percentage and Its Role in Health and Performance
Body fat percentage is a far more meaningful health marker than BMI or scale weight. BMI fails to differentiate between fat mass and lean mass — a muscular athlete and an overweight sedentary person of the same height can have identical BMIs despite vastly different body compositions and health profiles. Body fat percentage directly measures what BMI approximates: the proportion of your total weight that is adipose tissue versus lean mass (muscle, bone, organs, water).
The US Navy circumference method used by this calculator estimates body fat from height, neck, and waist measurements (plus hips for women) using a validated logarithmic formula. It achieves accuracy of ±3–4% compared to DEXA (dual-energy X-ray absorptiometry) — the gold standard body composition assessment — making it the most accessible accurate method available without laboratory equipment. The same method is used for military fitness screening by the US Army, Navy, and Air Force. Accuracy depends on consistent measurement technique: measure neck at the narrowest point (just below the larynx), waist at the narrowest point (usually between ribs and navel), and hips at the widest point for women.
For athletes, optimal body fat ranges depend on sport and goal. Strength sports (powerlifting, Olympic lifting): 12–18% for men, 18–25% for women — enough stored energy to support heavy training without excess mass impeding relative strength. Physique sports: stage-ready bodybuilders reach 4–7% (men) and 10–14% (women), which is not sustainable long-term without significant hormonal consequences. Endurance sports: elite marathoners typically run 8–12% (men), 14–18% (women) — minimizing excess fat mass that must be carried over long distances. The classifications in the table below represent the American Council on Exercise (ACE) guidelines, the most widely referenced body fat classification system in fitness professional education.
How to Measure Correctly
Use a flexible tape measure and measure at the narrowest point for waist, the largest point for hip, and just below the larynx for neck. Measurements should be taken first thing in the morning before eating for the most consistent results.