Use this free online body fat calculator to estimate your body fat percentage using the U.S. Navy circumference method. Enter your gender, height, neck, and waist measurements (plus hip measurement for women) to get your estimated body fat percentage and category. This tool provides general informational estimates only and is not a substitute for professional medical assessment.
The US Navy method was developed so that body fat could be estimated with nothing more than a measuring tape. Fat around the abdomen pushes the waist measurement up, while the neck is mostly bone, muscle and airway, so the gap between waist and neck tracks how much fat a person carries. Height is added to scale that gap to body size. For women, hip circumference is included because women store a larger share of fat around the hips and thighs.
The calculator uses base-10 logarithms of (waist − neck) for men, or (waist + hip − neck) for women, and of height, all in centimetres. The result is rounded to two decimal places and then placed in a category. Because the inputs are logarithms, a 1 cm error in the waist matters more for a lean person than for someone with a large waist.
Man, 175 cm tall, neck 38 cm, waist 90 cm: waist − neck = 52, log10(52) = 1.7160 and log10(175) = 2.2430. The denominator is 1.0324 − 0.19077 × 1.7160 + 0.15456 × 2.2430 = 1.0517. Then 495 ÷ 1.0517 − 450 = 20.66%, which falls in the Average band for men (18 to 24.9%).
Woman, 160 cm tall, neck 33 cm, waist 78 cm, hip 98 cm: waist + hip − neck = 143. Using the female formula, the estimate is 31.31%, at the top of the Average band for women (25 to 31.9%).
How the estimate changes with waist size alone, keeping the other measurements fixed:
| Waist (cm) | Man: 170 cm, neck 37 cm | Woman: 158 cm, neck 32 cm, hip 95 cm |
|---|---|---|
| 70 | — | 26.76% |
| 75 | 10.14% | 29.35% |
| 80 | 14.56% | 31.87% |
| 85 | 18.57% | 34.34% |
| 90 | 22.24% | 36.74% |
| 95 | 25.63% | 39.09% |
| 100 | 28.78% | — |
The categories follow the widely used American Council on Exercise (ACE) chart. Women naturally carry more essential fat than men, so every band is higher for women.
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5.9% | 10–13.9% |
| Athletes | 6–13.9% | 14–20.9% |
| Fitness | 14–17.9% | 21–24.9% |
| Average | 18–24.9% | 25–31.9% |
| Obese | 25% + | 32% + |
An Essential Fat result is not a goal. Fat at that level is needed for hormones, nerve function and organ protection, and staying there for long periods can be harmful, especially for women.
South Asians, including Indians, tend to carry more body fat, and more of it around the abdomen, than Europeans of the same BMI. This is why a person with a normal BMI can still have a high body fat percentage, sometimes called the thin-fat pattern. A body fat estimate can reveal this when BMI alone does not.
Your waist measurement is also useful by itself. Indian consensus guidelines treat a waist above 90 cm in men or 80 cm in women as abdominal obesity, linked with higher risk of diabetes and heart disease. If your waist is above these values or your estimate is in the Obese band, discuss it with a doctor. This calculator gives an estimate for general information and is not a medical diagnosis.