Body Fat Calculator

About the US Navy Body Fat Method

The US Navy method calculates body fat percentage from body measurements using a logarithmic formula developed by Hodgdon and Beckett. It requires only a tape measure and height, making it practical for regular tracking without specialized equipment.

For men, measurements needed are neck and waist circumference. For women, neck, waist (at narrowest point), and hip circumference are required. Measure in centimeters for best accuracy; take 2–3 readings at each site and average them.

US Navy Formula

Male: BF% = 495/(1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450 Female: BF% = 495/(1.29579 − 0.35004×log₁₀(waist+hip−neck) + 0.22100×log₁₀(height)) − 450

ACE Body Fat Categories

Category	Men	Women
Essential fat	2–5%	10–13%
Athletes	6–13%	14–20%
Fitness	14–17%	21–24%
Average	18–24%	25–31%
Obese	25%+	32%+

Frequently Asked Questions

The US Navy method has an error margin of approximately ±3–4% compared to DEXA scan (gold standard). It tends to overestimate body fat in very lean individuals and underestimate in very obese individuals. It is best used for tracking trends over time rather than as an absolute measurement.

Body fat percentage is generally more informative than BMI because it directly measures body composition — the ratio of fat to lean mass. BMI cannot distinguish between fat and muscle. A muscular athlete may have high BMI but low body fat; an inactive person may have normal BMI with high body fat.

Measure neck circumference just below the larynx (Adam's apple), with the tape held horizontally. Look straight ahead and relax your neck muscles. Do not compress the skin. For women, measure at the smallest part of the neck.

Healthy body fat ranges increase with age. At 20–39, healthy ranges are 8–20% (men) and 21–33% (women). At 40–59, healthy is 11–22% (men) and 23–35% (women). At 60–79, healthy is 13–25% (men) and 24–36% (women), according to the American Council on Exercise.