Body Fat Calculator

US Navy body fat estimate

If you're looking to calculate your BMI based on your height and weight, try our BMI Calculator.

cm
cm

Below the larynx (Adam's apple)

cm

At the navel

How it works

Enter your height and body measurements (neck, waist, and hip for women). The calculator uses the US Navy method to estimate your body fat percentage. This method only requires a tape measure and is accurate to approximately ±3-4%.

The US Navy method

Developed in the 1980s for military fitness screening, the US Navy method uses circumference measurements as a proxy for body fat. The logic is that the waist accumulates fat while the neck reflects lean muscle mass, so a large waist-to-neck ratio suggests higher body fat. Women add the hip measurement because fat distribution differs between sexes.

men: BF% = 86.01 × log10(waist - neck) - 70.041 × log10(height) + 36.76

women: BF% = 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387

Body fat categories

  • Essential fat: 2-5% (men) · 10-13% (women)
  • Athletic: 6-13% (men) · 14-20% (women)
  • Fitness: 14-17% (men) · 21-24% (women)
  • Average: 18-24% (men) · 25-31% (women)
  • Obese: 25%+ (men) · 32%+ (women)

Limitations

This is an estimate only. The Navy method can be less accurate for very muscular or very tall/short individuals, and circumference measurements are sensitive to technique (where exactly you place the tape). More precise methods include DEXA scans, hydrostatic weighing, and air displacement plethysmography, but these require clinical equipment. For general tracking the Navy method is a practical and repeatable option.

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