Fat Mass: "+fatMass+" lbs | Lean Mass: "+leanMass+" lbs";if(showSteps){var fStr=g==='male'?"495 / (1.0324 – 0.19077 * log10(waist-neck) + 0.15456 * log10(height)) – 450″:"495 / (1.29579 – 0.35004 * log10(waist+hip-neck) + 0.22100 * log10(height)) – 450″;document.getElementById('formulaSteps').innerHTML="Method: U.S. Navy Fitness Formula
Formula: "+fStr;document.getElementById('formulaSteps').style.display='block';}else{document.getElementById('formulaSteps').style.display='none';}}function resetBF(){document.getElementById('answer').innerHTML='';document.getElementById('hipRow').style.display='none';}
Using the Body Fat Percentage Calculator
The body fat percentage calculator is a specialized tool designed to estimate what portion of your total body weight is composed of fat versus lean tissue (muscle, bone, and water). Unlike a scale that only shows total weight, or a BMI calculator that only looks at height and weight, this calculator uses circumference measurements to provide a more detailed look at your physical composition.
To get the most accurate result, use a flexible measuring tape and take measurements directly against the skin. This tool is particularly useful for athletes and individuals on weight loss journeys who want to ensure they are losing fat rather than muscle.
- Height
- Your total height without shoes, measured in inches or centimeters.
- Neck
- Measure below the larynx (Adam's apple) with the tape slanting slightly downward to the front.
- Waist
- For men, measure at the navel. For women, measure at the narrowest part of the torso.
- Hips (Women only)
- Measure at the widest point of the buttocks.
How It Works: The U.S. Navy Method
When you use this body fat percentage calculator, it employs the "U.S. Navy Method," which was developed by the Naval Health Research Center. This method is highly regarded because it is non-invasive and provides a reliable estimate for most people without requiring expensive equipment like DXA scans.
Male Formula: %Fat = 86.010 × log10(waist – neck) – 70.041 × log10(height) + 36.76
Female Formula: %Fat = 163.205 × log10(waist + hip – neck) – 97.684 × log10(height) – 78.387
- Logarithmic Scaling: The formulas use log10 to account for the non-linear relationship between circumference and volume.
- Gender Differences: Formulas differ because women naturally carry more essential body fat in the hip and thigh region for reproductive health.
- Lean Body Mass: Once your fat percentage is found, we subtract that weight from your total weight to find your lean body mass.
Calculation Example
Example: A 30-year-old male weighing 190 lbs who stands 72 inches (6 feet) tall. His neck measurement is 16 inches and his waist is 36 inches.
Step-by-step solution:
- Height = 72 in, Neck = 16 in, Waist = 36 in
- Calculate (Waist – Neck) = 36 – 16 = 20
- Apply Logarithms: 86.010 * log10(20) – 70.041 * log10(72) + 36.76
- Math: (86.010 * 1.301) – (70.041 * 1.857) + 36.76
- Math: 111.90 – 130.07 + 36.76
- Result = 18.6% Body Fat
- Category: Fitness Range
Common Questions
Is this calculator as accurate as a DEXA scan?
While a DEXA scan is the "gold standard" of body composition analysis, the U.S. Navy method used in this body fat percentage calculator is generally accurate within 3-4% for most individuals. It is an excellent, free way to track progress over time as long as you use the same measurement technique each time.
What is a healthy body fat percentage?
For men, a healthy range is typically 14-24%. For women, it is 21-31%. Athletes often have lower percentages (6-13% for men and 14-20% for women). Falling below the "Essential Fat" level (2-5% for men, 10-13% for women) can lead to serious health issues and organ failure.
Why does the calculator ask for hip measurements for women?
Women store more fat in the hips and glutes due to hormonal differences (estrogen). The Navy formula includes this measurement to ensure it captures the full picture of a woman's fat distribution, providing a more accurate result than waist measurement alone.