Where should I measure my waist?
Men measure horizontally at the level of the navel. Women measure at the narrowest natural waistline between the ribs and navel.
Body Fat Calculator
The US Navy Circumference Method calculates body fat percentage and fat-free mass using standard body tape measurements (neck, waist, and hips) and height.
Scientific Formula & Exercise Physiology Standards
Equation: US Navy Circumference Equations (Hodgdon & Beckett) | Peer-Reviewed Source: Naval Health Research Center (Report 84-29)
Men: 495 ÷ [1.0324 - 0.19077(log(Waist-Neck)) + 0.15456(log(Height))] - 450
Female equation incorporates waist, hip, and neck circumferences. Logarithms are base 10 and all linear measurements are entered in centimeters.
Step-by-Step Worked Example: US Navy Body Fat Calculation (Male)
- Waist - Neck difference: 86 - 38 = 48 cm
- Calculate log10(48) = 1.68124 and log10(180) = 2.25527
- Compute body density denominator: 1.0324 - (0.19077 × 1.68124) + (0.15456 × 2.25527) = 1.0597
- Calculate Siri equation percentage: (495 ÷ 1.0597) - 450 = 17.1%
Calculation Result: Body Fat = 17.1% (Fitness Category)
Clinical Nuances, Limitations & Best Practices
- Tape tension must be consistent across multiple measurement trials.
- Does not replace DEXA scan or hydrostatic weighing gold standards.
Frequently Asked Questions (Body Fat Calculator)
Related Health & Fitness Calculators
BMI Calculator
Calculate your Body Mass Index (BMI) and determine your healthy weight range.
Calculate →Lean Body Mass Calculator
Calculate your lean body mass using Boer, James, and Hume clinical formulas.
Calculate →FFMI Calculator
Calculate Fat-Free Mass Index and Normalized FFMI to assess muscular development.
Calculate →Waist-to-Height Ratio Calculator
Evaluate cardiometabolic risk and visceral abdominal fat using the Ashwell shape chart.
Calculate →