Body Fat Percentage Calculator
Estimate body fat percentage from simple circumference measurements using the US Navy method. Enter your measurements in cm or inches.
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.
Related calculators
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.