Navy Body Fat Calculator — U.S. Navy Method
The U.S. Navy body fat formula is one of the most practical methods for estimating body fat percentage at home — all you need is a flexible tape measure. Developed by Hodgdon and Beckett at the Naval Health Research Center in 1984, the method uses circumference measurements (waist, neck, and hip for women) combined with height to predict body fat within ±3–4% of hydrostatic weighing, which was the gold standard at the time. The U.S. military still uses this method for fitness assessments, making it one of the most widely applied body fat equations in the world. This calculator implements the original published formula with metric and imperial support.
Your Measurements
Measure below Adam's apple
Measure at navel
Example Use Cases
A male, 180 cm tall, waist 85 cm, neck 38 cm: BF% ≈ 17.5%. This falls in the 'Fitness' category — typical for a recreationally active man.
A female, 165 cm tall, waist 75 cm, neck 32 cm, hips 100 cm: BF% ≈ 27.3%. This is within the 'Acceptable' category for women.
How to Interpret Your Results
The Navy method is most accurate for people with typical fat distribution patterns. It can overestimate body fat in people who carry fat primarily in their lower body and underestimate it in those with disproportionately large waists. For improved accuracy, take three measurements at each site and use the average.
Frequently Asked Questions
Methodology & Limitations
Formulas Used
**Navy Method (Men):** BF% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76. **Navy Method (Women):** BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387. **BMI Method (Men):** BF% = 1.20 × BMI + 0.23 × age − 16.2. **BMI Method (Women):** BF% = 1.20 × BMI + 0.23 × age − 5.4.
Page-Specific Notes
This page highlights the Navy method as the primary calculation. The Hodgdon-Beckett (1984) equations are used exactly as published.
Limitations
Circumference-based estimates have a standard error of ±3–4%. Results are less reliable for individuals with unusual fat distribution patterns, very lean athletes, or the elderly. For clinical accuracy, consider DEXA scanning.
Sources & Citations
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, Report No. 84-29. 1984.
- Deurenberg P, et al. Body mass index as a measure of body fatness. Br J Nutr. 1991;65(2):105-114.
Medical Disclaimer: This calculator provides estimates based on published formulas and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making changes to your diet or exercise routine.
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