Body Fat Percentage Calculator — U.S. Navy Method

The Formula

The U.S. Navy / Hodgdon & Beckett circumference method estimates body fat percentage from simple tape measurements. It uses the difference between trunk and neck circumferences relative to height, validated against hydrostatic weighing.

Variable Definitions

How to Use This Calculator

1. 1

   Select your unit system (Imperial or Metric).

2. 2

   Select your biological sex (affects which measurements are needed).

3. 3

   Enter your age, weight, and height.

4. 4

   Take neck measurement just below the larynx.

5. 5

   For Men: measure abdomen at navel level. For Women: measure waist at narrowest point and hip at widest point.

6. 6

   Review your estimated body fat %, fitness category, and fat/lean mass breakdown.

Common Applications

• Fitness progress tracking — monitor body fat percentage changes over time to evaluate the effectiveness of diet and exercise programs without needing expensive equipment
• Health risk assessment — body fat percentage categories (essential, athletic, fitness, average, obese) correlate with metabolic health markers and guide lifestyle interventions
• Military and tactical fitness — the U.S. Navy circumference method is used by multiple armed services for body fat estimation in personnel fitness assessments
• Body composition goal setting — estimate fat mass and lean mass from simple tape measurements to set informed body recomposition goals beyond just scale weight

Body fat categories range from essential fat (2-6% men, 10-14% women) to obese (25%+ men, 32%+ women)

Understanding the Concept

The U.S. Navy circumference method (Hodgdon & Beckett, 1984) is one of the most widely validated tape-measure body fat estimation techniques. Accuracy is ±2–3% compared to hydrostatic weighing when measurements are taken correctly. It works because subcutaneous fat distributes predictably: the difference between trunk and neck circumference correlates strongly with total body density. For the most accurate results, have someone else take your measurements, use a non-stretchable tape, and measure at the same time of day (morning is best, before meals). This method may overestimate body fat in very lean individuals and underestimate in the very obese. For clinical body fat assessment, methods like DEXA, Bod Pod, or hydrostatic weighing are more accurate. A practical tip: squeeze but do not compress the skin when measuring — the tape should be snug but not tight. Take each measurement 2–3 times and use the average. Measuring after a workout can give falsely low readings due to water loss and reduced subcutaneous fluid. Men and women store fat differently — men store more viscerally (around organs) which is harder to measure with circumference methods, while women store more subcutaneously (under the skin) especially around the hips and thighs. This is why different formulas are used for each sex.

Frequently Asked Questions

Sources & References