health ToolUpdated 2026-09-19
Body Fat Calculator
Estimate your body fat percentage and lean muscle mass using the official US Navy circumference measurement algorithm.
Important Medical Disclaimer: This health tool is designed solely for informational, screening, and educational purposes. It does not provide medical diagnosis, treatment, or individualized clinical advice. Always consult a qualified physician or healthcare provider regarding any health condition.
Formula & Mathematical Methodology
US Navy Body Fat Equation
Relies on the logarithmic ratio of abdominal waist and neck circumferences against total stature.
How to Use This Body Fat Calculator
- Measure waist at navel level and neck at narrowest point.
- Enter height and weight.
Step-by-Step Worked Example
Scenario: Waist 84 cm, Neck 39 cm, Height 178 cm
1. Circumference difference: 84 − 39 = 45 cm
2. Logarithmic evaluation yields approx 16.4% body fat
Final Calculated Result: 16.4% Body Fat (Fitness Category)
What Does Your Result Mean?
Classifies body composition: Athletes (6-13%), Fitness (14-17%), Average (18-24%), Obese (≥25% for men).
Common Practical Applications:
- Body composition tracking
- Bodybuilding and athletic conditioning
Important Limitations & Assumptions:
- Tape measure tension and hydration levels can introduce minor measurement variances.
Frequently Asked Questions
How accurate is the US Navy method?
When measured accurately, the US Navy method typically falls within 3% to 4% of dual-energy X-ray absorptiometry (DEXA) scans.
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