Body Fat Percentage Calculator: U.S. Navy Method

Estimate your body fat percentage using the U.S. Navy circumference method. Enter your height, neck, and waist measurements (plus hip for women) to get your body fat category, fat mass, and lean mass.

Mathematical Audit

U.S. Navy Body Fat Formula

The U.S. Navy method estimates body fat percentage from a small set of circumference measurements (neck, waist, and for women, hips) and height, using logarithmic relationships derived from a large study of Navy personnel. It requires only a tape measure and is typically accurate within about 3-4% of more advanced methods like DEXA scans.

Men: Body Fat % = 86.010 × log₁₀(Waist − Neck) − 70.041 × log₁₀(Height) + 36.76 (inches)
Women: Body Fat % = 163.205 × log₁₀(Waist + Hip − Neck) − 97.684 × log₁₀(Height) − 78.387 (inches)
Fat Mass = Body Weight × (Body Fat % ÷ 100); Lean Mass = Body Weight − Fat Mass

Measure your neck just below the larynx (Adam's apple), your waist at the navel (men) or narrowest point (women), and hips at the widest point (women). For best accuracy, measure to the nearest 0.5 cm or 1/4 inch and take measurements in the morning before eating.

Operational Guide

How to Use the Body Fat Percentage Calculator

1

Choose your unit system

Select Metric (cm) or Imperial (in) for your measurements.

2

Enter your sex, height, and weight

Weight is used to calculate your fat mass and lean body mass in addition to your body fat percentage.

3

Measure and enter your neck and waist

Measure your neck just below the larynx and your waist at the navel (men) or narrowest point (women).

4

Enter your hip measurement (women only)

Women should also measure around the widest part of the hips, as this measurement is required for the female formula.

5

Click Calculate

See your estimated body fat percentage, body fat category, fat mass, and lean body mass.

Real-World Scenario Example

"A man who is 178 cm tall, with a neck of 38 cm, a waist of 86 cm, and a weight of 80 kg wants to estimate his body fat percentage."

Inputs

unitSystem:metric
sex:male
heightCm:178
neckCm:38
waistCm:86
hipCm:95
weightKg:80

Result

Body Fat % ≈ 17.5%, which falls in the 'Fitness' category for men. Fat Mass ≈ 14.0 kg and Lean Mass ≈ 66.0 kg.

Important Disclaimer

This calculator provides an estimate of body fat percentage for informational purposes only and is not a substitute for medical or professional assessment. Accuracy depends on correct measurement technique and may vary by individual body type. Consult a healthcare provider for a complete body composition assessment.

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