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What is my body fat percentage?

Estimate your body fat percentage using the U.S. Navy method. Understand what your body composition means for fitness and health.

What This Calculator Is

A body fat percentage calculator estimates your body composition using body measurements. Unlike BMI, body fat percentage distinguishes between lean mass and fat mass, providing a more accurate picture of your health. This calculator uses the U.S. Navy method, which requires waist, neck, and (for women) hip measurements.

Who This Calculator Is For

Fitness enthusiasts tracking body composition, people whose BMI doesn't reflect their fitness level (athletes with high muscle mass), and anyone wanting a more nuanced understanding of their body than weight alone provides.

When to Use This Calculator

Use this calculator when starting or evaluating a fitness program, when tracking body composition changes (which matter more than scale weight), when you suspect BMI doesn't accurately reflect your health, or when setting realistic fitness goals.

Inputs

170
5
10
34
15
38

Results

Body Fat %

17.500%

Fat Mass29.8
Lean Mass140.2
Fitness CategoryFitness

Results are general guidelines, not medical advice. Consult a healthcare provider.

Insights

Your body composition

At 17.5% body fat, you're in the "Fitness" range for your gender.

Health focus

Body fat percentage is one metric—focus on overall fitness, energy levels, and how you feel.

How Body Fat Is Calculated

The U.S. Navy method uses circumference measurements and height to estimate body fat. For men: neck and waist. For women: neck, waist, and hip. The formula uses logarithmic calculations validated by the military.

Men: %BF = 86.010*log10(waist-neck) - 70.041*log10(height) + 36.76
Women: %BF = 163.205*log10(waist+hip-neck) - 97.684*log10(height) - 78.387
fatMass = weight * %BF/100; leanMass = weight - fatMass
Where:
waist, neck, hip in inches; height = total inches (feet*12+inches); weight in lbs
Assumptions:
US Navy circumference method; result clamped to range [2, 50]%
Returns 'Unknown' (0%) if waist<=neck or other invalid inputs
Category thresholds differ by gender (male: <6 Essential,<14 Athletic,<18 Fitness,<25 Average,else Above Average; female thresholds differ)

Key Takeaways

  • •Men: Essential fat 2-5%, Athletes 6-13%, Fitness 14-17%, Acceptable 18-24%, Obese 25%+
  • •Women: Essential fat 10-13%, Athletes 14-20%, Fitness 21-24%, Acceptable 25-31%, Obese 32%+
  • •Measure first thing in morning for consistency
  • •This method is an estimate — DEXA scans and hydrostatic weighing are more accurate
  • •Focus on trends over time rather than a single measurement

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