Free Tool · US Navy Method
Body Fat
Calculator.
Your body fat percentage, lean mass, and fat mass: calculated free from a tape measure in under 2 minutes.
Start CalculationUnderstanding the US Navy Method & ACE Classification
The Formula
For Men:
Body Density = 1.0324 − 0.19077 × log₁₀(Waist − Neck) + 0.15456 × log₁₀(Height)
%BF = 495 / Body Density − 450
All measurements in centimetres (cm) · Waist measured at navel · Density converted to %BF via the Siri (1961) equation
For Women:
Body Density = 1.29579 − 0.35004 × log₁₀(Waist + Hip − Neck) + 0.22100 × log₁₀(Height)
%BF = 495 / Body Density − 450
All measurements in centimetres (cm) · Waist at narrowest point · Hip at widest · Density converted to %BF via the Siri (1961) equation
ACE Body Fat Classification Chart
| Category | Men | Women | Health Implication |
|---|---|---|---|
| Essential Fat | 2–5% | 10–13% | Minimum needed for basic physiological function; not a target for the general population |
| Athlete | 6–13% | 14–20% | Very lean range, often seen in trained individuals |
| Fitness | 14–17% | 21–24% | Lean range, generally associated with favourable body composition |
| Acceptable | 18–24% | 25–31% | Common adult range; improve lifestyle if waist, BMI, or health markers are elevated |
| Obese | 25%+ | 32%+ | Higher body-fat range; consider waist, BMI, blood pressure, glucose, and lipid markers |
Method Accuracy Comparison
| Method | Error vs. DEXA | Equipment | Cost |
|---|---|---|---|
| US Navy (this tool) | ±3–4% | Tape measure | Free |
| Skinfold Calipers | ±3–5% | Calipers | Very Low |
| Bioelectrical Impedance (BIA) | ±3–5% | Smart scale | Low-Medium |
| Hydrostatic Weighing | ±1–2% | Water tank | Medium |
| DEXA Scan (gold standard) | Reference | X-ray machine | High |
References
1. Hodgdon JA, Beckett MB (1984). Prediction of percent body fat for U.S. Navy men from body circumferences and height (Report No. 84-11) and Prediction of percent body fat for U.S. Navy women from body circumferences and height (Report No. 84-29). Naval Health Research Center, San Diego, CA.
2. American Council on Exercise (ACE). Percent Body Fat Norms for Men and Women. ACE Fitness.
3. American College of Sports Medicine (ACSM) (2022). ACSM's Guidelines for Exercise Testing and Prescription. 11th Edition. Wolters Kluwer.
4. ISSN (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition.
5. NIN-ICMR (2024). Dietary Guidelines for Indians. National Institute of Nutrition, Hyderabad.
6. Ashwell M, Gunn P, Gibson S (2012). Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obesity Reviews, 13(3):275–286.
Fill in your measurements above for your personal result, category, and tailored diet & exercise guidance.
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