Body Fat % Calculator — Navy Method
Estimate your body fat percentage using the US Navy circumference method. No equipment needed — just a tape measure. Results include fat mass and lean mass.
Quick Answer
The US Navy body fat method estimates body fat % using neck, waist, and height circumferences (plus hip for women). Accuracy is approximately ±3–4% vs DEXA scanning. For men: 6–13% is athletic, 14–17% is fitness, 18–24% is average. For women: 14–20% is athletic, 21–24% is fitness, 25–31% is average.
How the Navy Method Works
The US Navy circumference method estimates body fat percentage using simple tape measure measurements — no body fat scales, calipers, or expensive equipment needed. For men, the formula uses neck circumference, waist circumference, and height. For women, it adds hip circumference. These measurements are entered into a validated logarithmic equation that estimates the percentage of your body weight that is fat tissue.
The formula for men: Body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. For women: Body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Measure waist at the narrowest point (naval level, relaxed), neck just below the larynx, and hips at the widest point of the buttocks.
Accuracy and Limitations
The Navy method has a margin of error of approximately ±3–4% compared to DEXA (dual-energy X-ray absorptiometry) scanning, the clinical gold standard. This makes it most useful for tracking trends over time rather than obtaining a precise absolute value. If your Navy method score today is 22% and in three months it is 19%, you can be confident meaningful change has occurred — even if the exact number carries some uncertainty.
Individual accuracy varies based on body proportions. The formula performs best for people with typical fat distribution patterns. It may be less accurate for those with unusual fat deposition patterns or very high or very low muscle mass. For the most accurate single-point measurement, DEXA scanning or hydrostatic weighing remain the standards of reference.
Understanding Your Result
Healthy body fat ranges differ substantially between men and women due to essential fat differences. Women require 10–13% essential fat for hormonal function and reproductive health; men require only 2–5%. Athletic men typically carry 6–13% body fat; athletic women 14–20%. The "average" ranges — 18–24% for men and 25–31% for women — reflect typical sedentary adult body composition rather than optimal health.
A result in the "obese" category does not define your health — it is a data point. Body fat percentage, BMI, waist-to-hip ratio, and metabolic blood markers together paint a much fuller picture than any single measurement. Use this result alongside our Waist-to-Hip Ratio Calculator and TDEE Calculator to build a complete, actionable picture of your body composition.
Measurement tips for accuracy
Take measurements in the morning before eating. Measure twice and average. Keep the tape level and snug but not compressing the skin. Measure consistently at the same time and conditions for reliable trend tracking.