Body Fat Percentage Calculator
Estimate body fat percentage from simple circumference measurements using the US Navy method. Enter your measurements in cm or inches.
Reviewed by Richard Ross · Last updated April 2026
How Body Fat Percentage Calculator works
The US Navy circumference method
The US Navy body fat formula estimates body fat percentage from circumference measurements. For men, it uses waist and neck circumference; for women, it adds hip measurement. The formula applies logarithmic transformation of measurement differences — the mathematical structure reflects the relationship between fat distribution patterns and total body fat. It was developed to provide a fast, equipment-free screening method for military fitness assessments.
Accuracy and limitations
The US Navy method typically estimates body fat within ±3–4 percentage points of more accurate methods like DEXA scanning and hydrostatic weighing. Measurement error matters: even a 1cm error in waist circumference changes the result by roughly 1%. The method is less accurate at very high or very low body fat levels. Consistent measuring technique (measuring in the same location, relaxed, not after eating) improves reliability.
Body fat categories
Body fat categories differ between men and women due to differences in essential fat (required for hormonal function and organ protection). For men: essential fat is 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, and obese 25%+. For women: essential fat is 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, and obese 32%+. These ranges are guidelines — health risks increase with body fat rather than following a step function at category boundaries.
More accurate methods
DEXA (dual-energy X-ray absorptiometry) scanning is the gold standard for body composition measurement, accurate to ±1–2%. Hydrostatic (underwater) weighing is similarly accurate but requires specialist equipment. Air displacement plethysmography (BodPod) and bioelectrical impedance analysis (BIA) are more accessible alternatives with moderate accuracy. The circumference method is practical for regular self-monitoring when equipment is unavailable.
Frequently asked questions
How do I measure my waist correctly?
Measure at the level of your navel (belly button), relaxed — not after sucking in your stomach. Keep the tape horizontal, parallel to the floor, and snug but not compressing the skin. Take the measurement after exhaling normally. Measuring consistently at the same time of day reduces variation.
What is a healthy body fat percentage?
For men, 6–24% is considered a healthy range, with 14–17% being the "fitness" zone. For women, 14–31% is healthy, with 21–24% being the fitness zone. Body fat above 25% for men or 32% for women is generally associated with increased health risks, though these are not hard clinical thresholds.
Can I reduce body fat through exercise alone?
Exercise, particularly resistance training and high-intensity interval training, can reduce body fat while maintaining or increasing muscle mass. However, nutrition plays a larger role in fat loss for most people — creating a calorie deficit through diet is typically more efficient than exercise alone. The most effective approach combines both.
What is essential body fat?
Essential fat is the minimum amount needed for normal bodily functions, particularly in women where it supports hormonal production and reproductive health. For men, essential fat is approximately 2–5%; for women, 10–13%. Body fat below these levels indicates severe malnutrition or eating disorders and carries serious health risks.
What is a healthy body fat percentage for men and women?
Healthy body fat ranges differ significantly by sex. For men: essential fat 2-5%, athletic 6-13%, fitness 14-17%, average 18-24%, obese 25%+. For women: essential fat 10-13%, athletic 14-20%, fitness 21-24%, average 25-31%, obese 32%+. Women require more essential fat for hormonal function and reproductive health. Body fat below essential levels impairs organ function and hormonal balance in both sexes.
How accurate are body fat scales and calculators?
Consumer bioelectrical impedance analysis (BIA) scales have an error margin of 3-5 percentage points compared to clinical methods. Hydration levels, time of day, recent food/exercise, and skin temperature all affect readings. Skinfold callipers are similarly operator-dependent. DEXA (dual-energy X-ray absorptiometry) scanning is the clinical gold standard, accurate to ±1-2%. Hydrostatic (underwater) weighing and air displacement plethysmography are also highly accurate. For tracking trends over time, use the same method consistently under the same conditions.
Can you lose body fat without losing weight?
Yes — body recomposition involves simultaneously losing fat and gaining muscle, keeping total weight roughly stable. This is most effective for beginners to resistance training, people returning after a break, those with significant body fat, or people on a slight calorie surplus. Recomposition is slower than a dedicated cut or bulk but avoids the aesthetically unfavourable phases of each. It requires sufficient protein (2g/kg+) and consistent resistance training.
How does body fat distribution affect health?
Where you store fat matters as much as how much you store. Visceral fat — stored around the abdominal organs — is more metabolically active and directly associated with insulin resistance, type 2 diabetes, cardiovascular disease, and inflammation. Subcutaneous fat (stored under the skin, especially on hips and thighs) is less harmful. Waist-to-hip ratio and waist circumference are better predictors of cardiometabolic risk than body fat percentage alone. Pear-shaped fat distribution (hips/thighs) is generally less harmful than apple-shaped (abdominal).
How do hormones affect body fat storage?
Several hormones regulate fat storage and mobilisation. Insulin promotes fat storage and inhibits fat release — chronic high insulin (from high-carb diets or insulin resistance) makes fat loss harder. Cortisol (the stress hormone) promotes abdominal fat storage. Testosterone supports muscle building and reduces fat storage in men. Oestrogen in women promotes fat storage around hips and thighs for reproductive purposes. Thyroid hormones regulate basal metabolic rate — hypothyroidism can cause weight gain. Disruptions to any of these systems affect body composition.
What body fat percentage should I aim for?
The optimal target depends on your goals and health status. For general health: men 10-20%, women 18-28% is associated with low cardiometabolic risk. For visible abs (often a gym goal): men 8-12%, women 16-19% is typically needed. Below 6% for men and 14% for women, hormonal disruption, immune impairment, and injury risk increase significantly. For older adults, slightly higher body fat is associated with lower mortality than for younger people — the relationship is not linear across the lifespan.
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This calculator provides estimates for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.