US Navy circumference method — enter measurements in any unit.
Men: BF% = 495 ÷ [1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)] − 450 Women: BF% = 495 ÷ [1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)] − 450
This calculator uses the U.S. Navy circumference method, developed by Hodgdon and Beckett (1984), which estimates body fat percentage from simple tape-measure circumferences and height. It is one of the most widely validated field methods for body composition assessment.
For Men:
Body Fat % = 495 ÷ [1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)] − 450
For Women:
Body Fat % = 495 ÷ [1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)] − 450
All measurements are in centimeters (cm). Logarithms are base-10.
⚠️ Disclaimer: This calculator is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult a qualified healthcare provider for a clinical body composition assessment.
Step 1: waist − neck = 85 − 38 = 47 cm
Step 2: log₁₀(47) = 1.67210
Step 3: log₁₀(178) = 2.25042
Step 4: Denominator = 1.0324 − (0.19077 × 1.67210) + (0.15456 × 2.25042)
= 1.0324 − 0.31901 + 0.34773
= 1.06112
Step 5: BF% = (495 ÷ 1.06112) − 450
= 466.47 − 450
= 16.47%Result: Estimated Body Fat: **~16.5%** — classified as "Fitness" range for adult males.
A result of 16.5% body fat for an adult male falls within the Fitness category (14–17% is often cited as fitness-level for men aged 20–39 by the American Council on Exercise). This means roughly 16.5 lbs of every 100 lbs of body weight is fat tissue. Values below 6% in men are considered essential fat only, while values above 25% are generally classified as obese. Use your result as a starting point for health discussions with your doctor, not as a clinical diagnosis.
The number on a scale doesn't distinguish between muscle, bone, water, and fat. Two people of identical weight and height can have dramatically different health profiles depending on their body composition. Body fat percentage gives a clearer picture of metabolic health, cardiovascular risk, and physical fitness.
| Category | Men | Women | |---|---|---| | Essential Fat | 2–5% | 10–13% | | Athletes | 6–13% | 14–20% | | Fitness | 14–17% | 21–24% | | Acceptable | 18–24% | 25–31% | | Obese | 25%+ | 32%+ |
The U.S. Navy circumference method has a margin of error of approximately ±3–4 percentage points compared to gold-standard methods like DEXA (dual-energy X-ray absorptiometry) or hydrostatic weighing. It consistently outperforms BMI for identifying excess body fat, particularly in muscular individuals where BMI can overestimate fatness.
A combination of a moderate caloric deficit (~300–500 kcal/day), resistance training to preserve lean mass, and cardiovascular exercise is the most evidence-supported strategy for reducing body fat percentage while maintaining or building muscle.
The most effective strategy is a moderate caloric deficit (300–500 kcal below maintenance), high protein intake (1.6–2.2 g per kg of body weight), and progressive resistance training at least 3 times per week. Rapid weight loss diets tend to cause significant muscle loss alongside fat loss.
Subcutaneous fat sits just beneath the skin and is what you can pinch. Visceral fat surrounds the internal organs in the abdominal cavity. Visceral fat is more metabolically active and is more strongly linked to cardiovascular disease, type 2 diabetes, and metabolic syndrome. Waist circumference is a proxy for visceral fat.
Because circumference measurements can fluctuate daily, it is best to remeasure every 4–8 weeks under consistent conditions (same time of day, same measuring tape, same measurer) to track meaningful trends rather than day-to-day noise.
No. The Navy formula was validated on adult populations. Body fat norms and distribution patterns differ significantly in children and adolescents. Pediatric body composition should be assessed by a healthcare professional using age- and sex-specific standards.
The Navy method has a typical margin of error of ±3–4 percentage points compared to DEXA scanning. It is more accurate than BMI for most individuals but less precise than hydrostatic weighing or air displacement plethysmography (Bod Pod).
No. Men use waist, neck, and height measurements. Women use waist, hip, neck, and height. The formula constants are also different because men and women naturally carry fat differently — women require the hip measurement to account for gynoid (lower-body) fat distribution.
According to the American Council on Exercise, a healthy ("acceptable") range is approximately 18–24% for men and 25–31% for women. Athletes typically fall in the 6–13% (men) and 14–20% (women) ranges. Essential fat minimums are ~2–5% for men and ~10–13% for women.
The Navy method loses accuracy at very high body fat levels (roughly above 35% for men and 40% for women) because the relationship between circumference and body fat becomes less linear. A healthcare provider may recommend a more precise method such as DEXA in those cases.
Morning measurements before eating or exercising tend to be most consistent. Waist circumference in particular can fluctuate by 1–3 cm throughout the day due to food, water, and bloating, which affects your result.
No. BMI (Body Mass Index) uses only height and weight and cannot distinguish fat from muscle. Two athletes with the same height and weight but different body compositions will have the same BMI but very different body fat percentages. Body fat percentage is generally considered a more meaningful health metric.
Only sources that have been reviewed are shown. Unverified citations are never published.