Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method. Enter height, waist, neck, and hip measurements for an instant estimate.
Formulas, assumptions, and rounding are documented in our calculator methodology.
Sex
Units
Measure waist at navel level (relaxed, not sucked in). Measure neck just below the larynx (Adam's apple), sloping downward.
Estimated Body Fat
19.8%
Acceptable
US Navy circumference method
Body Fat Categories
- Essential Fat (2–5%)
- Athletes (6–13%)
- Fitness (14–17%)
- Acceptable (18–24%)
- ← You
- Obese (25–25+%)
US Navy Circumference Method
The US Navy method uses three measurements for men (height, waist at navel, neck below larynx) and four for women (adding hip at widest point). The formula uses logarithmic relationships between these measurements to estimate body density and fat percentage. It was developed by Hodgdon and Beckett in 1984 and remains widely used because it requires only a tape measure.
Understanding Your Body Fat Category
Body fat is categorized by the American Council on Exercise (ACE) into five groups: Essential fat (the minimum for organ function), Athletes, Fitness (above-average fitness), Acceptable (healthy but not athletic), and Obese (elevated health risk). Your category depends on both your body fat percentage and your sex — women naturally carry more essential fat than men.
Limitations of Circumference-Based Estimates
Circumference methods cannot distinguish between visceral fat (around organs, higher health risk) and subcutaneous fat (under the skin). They are also sensitive to measurement technique — inconsistent tape placement can shift results by 2–3%. For clinical accuracy, consider DEXA scanning, hydrostatic weighing, or air displacement plethysmography (Bod Pod).
Frequently Asked Questions
- The US Navy method estimates body fat from circumference measurements. For men: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. For women, the hip measurement is also included. All measurements are in centimeters.
- The US Navy method typically falls within 3–5% of clinical body composition measurements like DEXA scans for most healthy adults. Accuracy varies with body shape, measurement consistency, and body composition.
- Measure at the navel (belly button) level while relaxed — do not suck in your stomach. Use a flexible tape measure held snug but not compressing the skin.
- Women typically carry more fat in the hip/gluteal region. The female Navy formula accounts for this by including hip circumference (measured at the widest point) alongside waist and neck.
- ACE guidelines: Men — Essential fat 2–5%, Athletes 6–13%, Fitness 14–17%, Acceptable 18–24%, Obese 25%+. Women — Essential fat 10–13%, Athletes 14–20%, Fitness 21–24%, Acceptable 25–31%, Obese 32%+.