Get an accurate body fat percentage estimate using the US Navy method — a reliable field technique used by military fitness programs worldwide. All you need is a tape measure.
Body fat percentage is the share of total body mass composed of adipose tissue. The U.S. Navy circumference method estimates it from neck, waist, and height (plus hip for women) using logarithmic equations validated for field use. For men: BF% = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450. For women, waist and hip are combined minus neck in the log term. Typical adult male ranges often span roughly 6–25% for athletic to acceptable categories; women commonly run higher essential-fat minimums, often near 14–32% across similar bands. Tape measurements in centimetres or inches must be taken consistently at the navel-level waist and below the larynx for the neck. Accuracy is typically within a few percentage points of DXA methods when measurements are taken consistently. Essential fat minimums differ by sex because of hormonal roles. Hydration and meal timing can shift results slightly, so track trends rather than single readings.
Worked example: A man 175 cm tall with neck 38 cm and waist 85 cm: waist − neck = 47 cm. Plugging into the Navy formula yields about 18.4% body fat — often classified in the fitness range for males.
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Evidence-based strategies for body recomposition.
Consuming 1.6–2.2g protein per kg body weight while in a caloric deficit preserves muscle mass during fat loss. This is the most critical dietary lever for improving body composition.
Resistance training 3–4x per week stimulates muscle protein synthesis and increases resting metabolic rate. Even at the same body weight, more muscle means lower body fat percentage.
Sleep deprivation shifts weight loss from fat to muscle. In one study, dieters who slept 8.5 hours lost 55% fat vs. 25% fat for those who slept 5.5 hours on identical diets.
Circumference-based estimates are practical screening tools, not DEXA-level precision. Hydration, meal timing, and measurement technique can shift results by one to two percentage points. Focus on trend direction and category band rather than decimal perfection.
Body fat measurement explained.
For men: 6–13% athletic, 14–17% fitness, 18–25% acceptable. For women: 14–20% athletic, 21–24% fitness, 25–31% acceptable. Below essential fat ranges (<5% men, <13% women) risks organ damage.
The US Navy method is accurate within 3–4% compared to DEXA scan results for most people. It's less accurate for very muscular or very obese individuals. Use it to track trends rather than as an absolute measurement.
Use a flexible tape measure. Measure consistently: same time of day, after exhaling normally. Don't pull the tape tight — it should rest gently against the skin. Take 2–3 readings and average them for accuracy.
A realistic rate is 0.5–1% body fat reduction per month when following a proper protocol. Noticeable changes in body composition typically become visible after 6–12 weeks of consistent caloric deficit plus resistance training.
Body fat percentage is a more accurate health indicator because it distinguishes muscle from fat. A 90kg athlete with 12% body fat is far healthier than a 90kg sedentary person with 30% body fat, even if their BMI is identical.
Get the full picture of your body composition.
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Browse All Tools →Circumference-based body-fat estimates follow the U.S. Navy method used in field screening. Accuracy depends on consistent tape landmarks:
This calculator gives a general estimate for education and planning. It is not a medical diagnosis and does not replace advice from a qualified healthcare professional. Talk to your doctor before acting on these results — especially if you are pregnant, under 18, or managing an existing medical condition.