📊 US Navy Method · BMI Estimation

Body Fat
Percentage Calculator

Estimate your body fat percentage with simple tape measurements — no expensive equipment needed.

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Body Fat Calculator

📏 How to measure: Use a flexible measuring tape. Measure at the widest point for each area. Take 2–3 measurements and average them. Measure in the morning before eating.
👤 Biological Sex
cm
Enter height
kg
📐 Tape Measurements (US Navy Method)
cm
Enter waist circumference
At navel level, relaxed
cm
Enter neck circumference
Just below larynx
Body Fat
Fat Mass
Lean Mass
Fitness Category
CategoryWomenMen
Essential Fat10–13%2–5%
Athletes14–20%6–13%
Fitness21–24%14–17%
Average25–31%18–24%
Obese32%+25%+
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How Body Fat Percentage Is Measured

Body fat percentage is the proportion of your total body weight that consists of fat tissue. Unlike BMI, which only considers height and weight, body fat percentage directly assesses body composition — making it a more informative health metric.

The US Navy Method (Circumference Method)

Developed by the US Department of Defense, this method uses body circumference measurements to estimate body fat percentage with reasonable accuracy (within 3–4% of DEXA scan results for most people). It requires only a measuring tape — no special equipment needed.

Male formula: % BF = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450

Female formula: % BF = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450

Body Fat % vs. BMI: Which Is Better?

Both metrics have their place in health assessment:

MetricMeasuresEquipmentAccuracy
BMIHeight-to-weight ratioScale, rulerModerate — misclassifies muscular people
Circumference (Navy)Body fat estimateTape measureGood — ±3–4% vs DEXA
Skinfold CalipersSubcutaneous fatCalipersGood when done correctly
DEXA ScanFull body compositionX-ray scannerExcellent — gold standard
Hydrostatic weighingBody densityWater tankExcellent

Body Fat Categories (American Council on Exercise)

CategoryWomenMenNotes
Essential Fat10–13%2–5%Minimum for survival; hormonal function
Athletes14–20%6–13%Competitive sports performance level
Fitness21–24%14–17%Active, health-conscious individuals
Average25–31%18–24%Typical for sedentary healthy adults
Obese32%+25%+Associated with increased health risks
⚠️ Note: Women naturally carry higher body fat than men, even at the same fitness level. This is physiologically normal and necessary for reproductive health and hormonal balance.

❓ FAQ

The US Navy circumference method is generally within 3–4% of DEXA scan results for most adults when measurements are taken correctly. It tends to be less accurate for very lean individuals (below 10% BF for men) and very obese individuals. For best accuracy, take 2–3 measurements of each site and average them.
For general health, most guidelines suggest 14–24% for women and 6–17% for men as optimal (fitness to athlete range). The "average" range (25–31% women, 18–24% men) is still considered healthy by most standards. The key is avoiding the extremes — both very low and very high body fat are associated with health problems.
Yes — this is called "normal weight obesity" or "skinny fat." It occurs when someone appears to be a healthy weight by BMI standards but has an unusually high body fat percentage and low muscle mass. It's associated with similar metabolic risks as conventional obesity. This is one reason why measuring body composition (not just BMI) provides a more complete health picture.
⚕️ Medical Disclaimer: Body fat estimates are approximations. For clinical purposes, use DEXA scanning or professional assessment. Consult a healthcare provider for personalized body composition advice.