Body Fat Calculator
Estimate body fat % with the US Navy circumference method
Body Fat Percentage
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Frequently Asked Questions
How does the US Navy body fat formula work?
The Navy method uses circumference measurements and height to estimate body density, then converts to body fat %. For men: uses waist and neck. For women: waist, hip, and neck. It's accurate to within 3–4% of DEXA scans.
Where exactly do I measure?
Neck: just below the larynx (Adam's apple), slight downward slope forward. Waist: at the navel level, not the narrowest point. Hip (women): at the widest point around the buttocks. Measure in the morning, before eating.
What is a healthy body fat percentage?
Men: 6–13% athletic, 14–17% fit, 18–24% average. Women: 14–20% athletic, 21–24% fit, 25–31% average. Essential fat (minimum for organ function) is 2–5% for men and 10–13% for women.
Is the Navy method accurate?
The US Navy formula has a margin of error of ±3–4% compared to gold-standard DEXA scans. It's more accurate than BMI for estimating adiposity but less accurate than hydrostatic weighing or DEXA. Best used for tracking trends over time.
Body Fat Categories
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fit | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
How to Measure Accurately
- • Measure in the morning before eating
- • Use a flexible tape measure, not rigid
- • Pull tape snug but don\'t compress skin
- • Take 2–3 readings and average them
- • Waist: at navel, not narrowest point
Body Fat vs BMI: What\'s the Difference?
BMI (Body Mass Index) measures weight relative to height — it can\'t distinguish between muscle and fat. Body fat percentage directly measures what fraction of your weight is fat tissue, making it a much better indicator of health and fitness.
A 200 lb bodybuilder and a 200 lb sedentary person have the same BMI, but the bodybuilder might have 8% body fat while the sedentary person might have 28%. Only body fat measurement reveals this difference.
Body Fat Measurement Methods Compared
Gold standard; uses X-ray to differentiate bone, fat, and lean mass. Costs $50–$100 at medical facilities.
Highly accurate; measures body density by underwater weight. Requires full submersion.
Very accurate; measures body volume using air displacement. Found at universities and gyms.
What this calculator uses. Uses circumference measurements. Free and convenient.
Bioelectrical impedance. Highly variable based on hydration. Good for trends, not absolute accuracy.
Accurate when done by a professional. Requires 3–7 pinch sites depending on protocol.