Estimate your body fat percentage and lean body mass using the U.S. Navy circumference method, plus your ideal healthy range.
Load profiles to check calculations:
Fill in your physical circumferences to predict biological body fat levels.
Your body fat range falls within the standard classification criteria.
The U.S. Navy Method estimates body fat percentage from simple circumference measurements rather than calipers or DEXA scans, using a regression formula developed by Hodgdon & Beck...
Understanding the difference between weight and body fat, and how to track fitness progress.
BMI (Body Mass Index) only evaluates total weight relative to height. It cannot tell the difference between heavy muscle mass and adipose fat tissue. Body Fat calculations measure actual body composition, giving a clearer picture of metabolic health and cardiovascular risk profiles.
Lean Body Mass (LBM) encompasses everything in your body except stored fat: muscles, bones, water, blood volume, and structural organs. Essential body fat is necessary for hormone manufacturing, cell protection, and vitamin absorption, while storage fat serves as energy reserves.
To improve your body composition:
For men, body fat % = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450, using centimeter measurements. For women, the formula also includes hip circumference: 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450.
Women naturally store more essential fat around the hips and pelvis, so the female formula factors in hip circumference to reflect that distribution, while the male formula relies only on neck and waist. The waist measurement must always exceed the neck measurement, and results are capped between 2% and 60% to stay within physiologically realistic bounds.
For a man who is 178 cm tall with a 38 cm neck and an 85 cm waist, the calculated density is about 1.0613, giving an estimated body fat of (495 / 1.0613) - 450, or roughly 16.4%. This places him in a generally lean, healthy range for an adult male.
Since body fat percentage reflects composition rather than just scale weight, compare your result against the BMI Calculator to see the difference, and use the Lean Body Mass Calculator to see how much of your weight is fat-free tissue.
Quick answers about how this tool works.
Women naturally store more essential fat in the pelvic and hip regions due to biological and reproductive factors. The female U.S. Navy formula incorporates hip circumference alongside waist and neck to accurately reflect these differences.
Healthy ranges vary by gender and age. Generally, the acceptable range is 14-24% for men and 21-31% for women. Athletic ranges are lower (6-13% for men, 14-20% for women). Values below essential levels (2% for men, 10% for women) or above obese thresholds are discouraged.
Body fat percentage is the proportion of your total body weight that consists of fat tissue. It provides a more detailed picture of body composition than weight alone and helps assess overall fitness and health.
This calculator uses the U.S. Navy Body Fat Formula, which estimates body fat percentage using measurements such as height, neck, waist, and hip circumference (for women). The formula is widely used because it is simple and reasonably accurate.
Most users need their height, neck circumference, and waist circumference. Women must also provide hip circumference because body fat distribution differs between men and women.
BMI estimates whether your weight is appropriate for your height but does not distinguish between muscle and fat. Body fat percentage directly measures the amount of fat in your body, making it a more useful indicator of body composition.
Yes. Athletes and individuals with high muscle mass may have a BMI classified as overweight while maintaining a low body fat percentage. This is one reason body fat percentage is often considered more informative than BMI.
For most people, measuring body fat once every 2 to 4 weeks is sufficient. Daily measurements are not recommended because normal fluctuations in hydration and body composition can affect results.
Yes. Combining a balanced diet with strength training and regular physical activity can help reduce body fat while preserving or even increasing muscle mass. Gradual and sustainable changes typically produce the best results.
Plain-language explainers that sit next to this tool.
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