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Body Fat % Calculator

Estimate body fat percentage with the US Navy method. Male and female, metric and imperial. See your category and fitness level.

Health Disclaimer: This calculator uses the US Navy method to estimate body fat percentage. Results are approximations and should not be used as a medical diagnosis. Body fat percentage varies with age, ethnicity, and fitness level. Consult a healthcare professional for accurate body composition analysis and before making any health decisions.

How to Use This Calculator

  1. Select your sex (male or female) — the formula uses different measurement sites.
  2. Choose your unit system: Imperial (inches) or Metric (centimeters).
  3. Enter your height, neck circumference, and waist circumference.
  4. If female, also enter your hip circumference.
  5. Click Calculate to see your estimated body fat percentage, category, and lean mass.

Real-World Examples

Athletic Male Assessment

Male, 6'0" (72 in) tall, 15.5" neck, 32" waist. Weight: 180 lbs.

Result: Body fat: 12.8%. Category: Athletic. Lean mass: 157 lbs. Fat mass: 23 lbs. Excellent fitness level for general health.

Average Female Assessment

Female, 5'5" (65 in) tall, 13" neck, 30" waist, 38" hips. Weight: 150 lbs.

Result: Body fat: 28.2%. Category: Average. Lean mass: 108 lbs. Fat mass: 42 lbs. Within healthy range.

Fitness Progress Tracking

Male started at 40" waist, now at 35" waist after 6 months. Height 5'10", neck 16".

Result: Before: 25.1% (obese). After: 18.9% (average). Lost approximately 6.2% body fat — significant improvement in health markers.

Common Mistakes to Avoid

  • Measuring waist at the hips instead of at the natural waistline (above the belly button).
  • Compressing the tape measure too tightly, which gives inaccurate (lower) measurements.
  • Not measuring neck at the correct point (should be just below the larynx/Adam's apple).
  • Comparing body fat percentages to BMI categories — they use different scales and meanings.

The Formula

Male: %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. Female: %BF = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387. (US Navy Method, using circumference measurements.)

Learn More

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Army vs Navy vs Marines Body Fat Standards Compared

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Frequently Asked Questions

The US Navy method is accurate to within 3-4% of hydrostatic (underwater) weighing for most people. It is less accurate for very muscular individuals or those with unusual fat distribution patterns. It is the standard method used by the US military for fitness assessments.

Methodology & Sources

Body fat estimated via the U.S. Navy circumference method (Hodgdon & Beckett, 1984) and U.S. Army ABCP tape test. Formulas validated against hydrostatic weighing.

Military Body Fat Standards

Military body fat standards differ by branch and are tightly regulated. The US Navy publishes its standards in OPNAVINST 6110.1K. The US Army publishes AR 600-9, currently implemented by ALARACT 087/2025 (10 Sep 2025). The US Marine Corps publishes MCO 6110.3A w/Change 3 (23 Feb 2021), currently modified by MARADMIN 066/26 (27 Feb 2026, waist-to-height pre-screen). Each branch sets its own maximum body fat percentages by age bracket and sex, and failing the body composition assessment has real consequences for service members.

Navy and Marines use the DoD-standard Hodgdon-Beckett circumference formula (height, neck, waist, and hip for women). The Army switched to a distinct one-site formula in 2023 that uses only abdomen circumference and body weight. For branch-specific pass/fail compliance verdicts with citations to the current regulation, use the dedicated branch calculators below.