Body Fat Percentage Calculator
Estimate your body fat percentage and determine your body composition using the widely accepted U.S. Navy Method.
Your Measurements (US Navy Method)
Your Body Composition
Enter your personal data and measurements to find out your estimated body fat percentage.
How to Use the Body Fat Calculator (U.S. Navy Method)
This calculator employs the U.S. Navy Body Fat Formula, which uses simple circumference measurements to estimate your body fat percentage. While not as precise as DEXA scans, it is highly practical and surprisingly accurate for tracking progress.
- Input Personal Data: Select your Gender and enter your Age, Height, and Weight.
- Choose Units: Select either Imperial (inches/lbs) or Metric (cm/kg). The calculator will automatically handle all necessary conversions before applying the formula.
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Take Circumference Measurements: Accuracy is key! Use a flexible tape measure for the following:
- **Neck:** Measure just below the larynx (Adam's apple), keeping the tape level.
- **Waist/Abdomen:** For men, measure horizontally at the navel. For women, measure at the narrowest point of the waist.
- **Hip (Females Only):** Measure horizontally around the widest part of the hips/buttocks.
- Interpret the Results: The calculator will output your Body Fat Percentage and compare it to standard fitness categories (Essential Fat, Athletes, Fitness, Average, Obese).
Why Tracking Body Fat is More Important Than Weight
Weight alone can be misleading. A body fat calculation provides a deeper look into your body composition—the ratio of fat mass to lean mass (muscle, bone, organs). During fitness transformations, especially while resistance training, your body weight may remain the same or even increase due to muscle gain, even while you are losing fat.
Tracking your body fat percentage is the most reliable way to monitor if you are truly succeeding in building a healthier, leaner physique. It helps you set realistic goals for improving health markers and athletic performance.
Important Information: Formulas and Health Categories
The U.S. Navy Method relies on the fact that fat tissue is less dense than muscle tissue. By using circumference measurements in conjunction with height, the formula estimates overall body volume and density to derive the percentage.
The Simplified US Navy Formula (Measurements in Inches)
$$\text{Male Body Fat \%} = 86.010 \times \log_{10}(\text{Waist} - \text{Neck}) - 70.041 \times \log_{10}(\text{Height}) + 36.76$$ $$\text{Female Body Fat \%} = 163.205 \times \log_{10}(\text{Waist} + \text{Hip} - \text{Neck}) - 97.684 \times \log_{10}(\text{Height}) - 78.387$$
Standard Body Fat Percentage Categories (ACSM)
| Category | Women (%) | Men (%) |
|---|---|---|
| Essential Fat | 10 - 13% | 2 - 5% |
| Athletes | 14 - 20% | 6 - 13% |
| Fitness | 21 - 24% | 14 - 17% |
| Average | 25 - 31% | 18 - 24% |
| Obese | 32% + | 25% + |
Frequently Asked Questions (FAQ)
How accurate is the U.S. Navy Body Fat Calculator?
It's generally considered accurate to within 1-3 percentage points of laboratory methods like Hydrostatic Weighing or DEXA scan, provided the measurements are taken consistently and correctly. It is excellent for tracking *changes* over time.
What is "Essential Fat"?
Essential fat is the minimum amount of fat necessary for basic bodily functions (hormone production, vitamin absorption, maintaining body temperature). Falling below the essential fat range is dangerous and harmful to health.
Should I measure in the morning or evening?
Always measure at the same time and under the same conditions for consistency. The morning, before eating or working out, is generally considered the best time as it minimizes fluctuations from food, hydration, and activity.
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