Enter your measurements to estimate your body fat percentage
This calculator uses the US Navy circumference method, which estimates body fat percentage from neck, waist, and hip measurements (hip for women only) along with height. The formula was developed by Hodgdon and Beckett at the Naval Health Research Center and is used for military fitness assessments worldwide.
For men: %BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
For women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
BMI uses only weight and height, which means it cannot distinguish between muscle and fat. A muscular athlete can have a high BMI but low body fat, while someone with little muscle may have a normal BMI but high body fat (sometimes called skinny fat). Body fat percentage provides a more accurate picture of body composition and health risk than BMI alone.
Measure your neck at the narrowest point, just below the Adam's apple. Measure your waist at the navel (belly button level), not at the narrowest point. For women, measure hips at the widest point of the buttocks. Use a flexible tape measure pulled snug against the skin without compressing it. Measure first thing in the morning for the most consistent readings.
Body fat percentage is directly linked to metabolic health. Excess visceral fat (around organs) increases the risk of type 2 diabetes, heart disease, and certain cancers, even in people with a normal BMI. Tracking body fat percentage over time is more informative than tracking weight alone, especially during body recomposition when you may be losing fat and gaining muscle simultaneously.
The US Navy method has a standard error of about 3–4% compared to DEXA scanning. It is more accurate than BMI for most people and is considered reliable enough for military fitness assessments. Hydrostatic weighing and DEXA scans provide higher accuracy but require specialised equipment.
For men, 14–24% is considered healthy. For women, 21–31% is healthy. Athletes typically maintain lower levels: 6–13% for men and 14–20% for women. Going below essential fat levels (2–5% for men, 10–13% for women) is dangerous and unsustainable.
Yes — this is called body recomposition. By gaining muscle while losing fat, your weight may stay the same or even increase while your body fat percentage drops. Resistance training combined with adequate protein intake (1.6–2.2g per kg of body weight) supports this process.
Every 2–4 weeks is sufficient. Body fat changes slowly, and daily measurements introduce more noise from hydration and measurement variation than meaningful data. Use the same method and conditions each time for the most consistent tracking.
Women carry more essential fat for reproductive and hormonal functions. Breast tissue, reproductive organs, and hormonal regulation require approximately 10–13% body fat in women versus 2–5% in men. This biological difference means healthy body fat ranges are about 8–10 percentage points higher for women across all categories.