Body Fat Percentage Calculator
Estimate your body fat percentage using the US Navy circumference method.
The US Navy body fat method
This calculator uses the US Navy circumference method, a body fat estimation technique developed for military fitness assessments that only requires a tape measure — no calipers or scans needed. For men, it uses neck and waist circumference along with height; for women, it adds hip circumference to the calculation. While not as precise as DEXA scans or hydrostatic weighing, it's been validated in numerous studies as a reasonably accurate field method for tracking body composition changes over time.
How the calculation works
The formula uses logarithms of your circumference measurements. For men: body fat % = 495 / (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450. For women: body fat % = 495 / (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450. Measure your neck just below the larynx, your waist at the navel, and (for women) your hips at the widest point, all with a flexible tape measure held snug but not compressing the skin.
Understanding your category
Body fat categories differ by sex because women naturally carry more essential fat for hormonal and reproductive function. This calculator uses standard American Council on Exercise (ACE) ranges — essential fat, athletic, fitness, average, and obese — to help you interpret your result. This is an estimate only and not medical advice; for clinical accuracy, consider a DEXA scan or consult a healthcare provider.
Frequently Asked Questions
How accurate is the US Navy body fat method?
Studies suggest the Navy method is typically accurate within about 3-4% of body fat compared to more precise methods like DEXA scans or hydrostatic weighing, making it a solid low-cost option for tracking trends over time even if it's not perfectly precise for any single measurement.
Where exactly do I measure my waist and neck?
Measure your neck circumference just below the larynx (Adam's apple), and your waist at the navel while relaxed (not sucked in). For hip measurements (women), measure at the widest point around the buttocks. Keep the tape snug but not compressing the skin.
Why do men and women use different formulas?
Women naturally carry more essential fat than men due to hormonal and reproductive needs, and fat is typically distributed differently between the sexes. The Navy method accounts for this with separate formulas — the female version also factors in hip circumference.
What is a healthy body fat percentage?
For men, "average" body fat is typically 18-24%, with "fitness" level around 14-17%. For women, "average" is typically 25-31%, with "fitness" level around 21-24%. Athletes often measure lower than these ranges, while going below "essential fat" levels (2-5% men, 10-13% women) can be unhealthy.
Why is my body fat percentage different from my BMI category?
BMI only considers height and weight, while body fat percentage estimates actual body composition. A muscular person can have a "high" BMI while still having a low, athletic body fat percentage — which is why body fat percentage is often considered more informative for fitness-focused individuals.
How can I lower my body fat percentage?
A sustained calorie deficit combined with resistance training tends to be the most effective approach, since it helps you lose fat while preserving (or building) lean muscle mass. Our calorie deficit calculator can help you find an appropriate daily calorie target.
Is this more accurate than a body fat scale?
Consumer body fat scales use bioelectrical impedance, which can be heavily affected by hydration levels and tends to fluctuate day to day. The Navy circumference method is generally considered more consistent for tracking gradual body composition changes, though neither replaces clinical-grade testing.
Is this body fat calculator medical advice?
No. This tool provides a mathematical estimate for informational and fitness-tracking purposes only. It is not a substitute for clinical body composition testing or advice from a qualified healthcare provider.