dopecalc

Body Fat Calculator

Estimate your body fat percentage using the US Navy method based on circumference measurements.

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About this Calculator

Estimate your body fat percentage using the US Navy method based on circumference measurements.

Formula & Calculations

Formula

Male: 86.010 × log₁₀(waist - neck) - 70.041 × log₁₀(height) + 36.76 | Female: 163.205 × log₁₀(waist + hip - neck) - 97.684 × log₁₀(height) - 78.387
Where:
  • BF%=Estimated body fat percentage
  • L=Logarithm base 10 of the key circumference measurement
  • waist=Waist circumference at the narrowest point (cm)
  • neck=Neck circumference measured below the larynx (cm)
  • hip=Hip circumference at the widest point (cm, females only)
  • height=Standing height in centimeters

Assumptions

  • The US Navy method provides an estimate and may deviate from DEXA or hydrostatic weighing results.
  • Measurements must be taken with a flexible tape measure against bare skin.
  • Formula accuracy decreases at extreme body fat levels (very lean or very obese).

Calculation Examples

Example 1

Inputs:Male, Height: 180 cm, Neck: 38 cm, Waist: 85 cm
Result:Body Fat: ~18.2% (Acceptable)

Using the male US Navy formula: 86.010 × log₁₀(85 - 38) - 70.041 × log₁₀(180) + 36.76 ≈ 18.2%.

Example 2

Inputs:Female, Height: 165 cm, Neck: 32 cm, Waist: 74 cm, Hip: 96 cm
Result:Body Fat: ~26.8% (Acceptable)

Using the female formula: 163.205 × log₁₀(74 + 96 - 32) - 97.684 × log₁₀(165) - 78.387 ≈ 26.8%.

Frequently Asked Questions

How accurate is the US Navy body fat formula?

The US Navy method is generally accurate within 3-4% for most individuals. It was developed using a large sample of military personnel and correlates well with underwater weighing. However, it may be less precise for very lean athletes or individuals with unusual fat distribution.

What is a healthy body fat percentage?

For men, 14-17% is considered fit and 18-24% is acceptable. For women, 21-24% is fit and 25-31% is acceptable. Essential fat is 2-5% for men and 10-13% for women.

Why do men and women use different formulas?

Men and women store body fat differently. Women naturally carry more essential fat for reproductive health, and fat distribution patterns differ between sexes. The US Navy developed separate regression equations to account for these physiological differences.