Body Fat Calculator — US Navy Circumference Method
Estimate your body fat percentage using the US Navy method with waist, neck, and hip measurements. No calipers or expensive equipment needed.
The US Navy Body Fat Estimation Method
The US Navy circumference method estimates body fat percentage from simple tape measurements — no expensive equipment, no body fat scale, and no calipers required. Developed for use in military fitness assessments, it's been validated against more precise methods like DEXA scanning and hydrostatic weighing and shows reasonable accuracy for general screening purposes.
Women: %BF = 163.205 × log₁₀(waist + hips − neck) − 97.684 × log₁₀(height) − 78.387
How to Take Accurate Measurements
- Waist: Measure at the narrowest point (men: at the navel level; women: at the narrowest part)
- Neck: Measure just below the larynx (Adam's apple), angled slightly downward toward the front
- Hips (women only): Measure at the widest point, usually across the fullest part of the buttocks
- Pull the tape firm but not compressing the skin. Take each measurement twice and average them.
Healthy Body Fat Percentage Ranges
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Acceptable / Healthy | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Why Body Fat % Is More Useful Than BMI Alone
BMI treats all body weight equally, while body fat percentage specifically measures the ratio of fat to lean mass. Two people with identical BMIs can have drastically different body compositions — a bodybuilder and a sedentary person may share the same BMI, but the athlete has far more muscle and less fat. Body fat percentage captures this critical distinction.
For weight loss goals, tracking body fat (not just scale weight) is especially important because muscle gain and fat loss can leave your scale weight unchanged while your body composition improves significantly.