Body Fat Calculator (U.S. Navy Method)
Estimate your body fat percentage instantly. Our free Body Fat Calculator uses standard Navy formulas and processes your health data locally in your browser for complete privacy.
What is the Body Fat Calculator?
Tracking weight alone doesn't tell the full story of your health; body fat percentage is a far better metric for fitness. This calculator uses the widely accepted U.S. Navy formula, which estimates body fat based on waist, neck, and hip circumferences relative to your height. Because health data is deeply personal, this tool was built to prioritize your privacy. The JavaScript calculation engine runs entirely locally on your device, ensuring your body measurements are never uploaded, logged, or shared with third parties.
Why Use Our Body Fat Calculator?
- Scientific Estimation: Uses the established U.S. Navy measurement algorithm.
- Instant Feedback: Results are calculated instantly as you type.
- Absolute Privacy: Client-side processing guarantees your health data is secure.
- Fitness Tracking: Helps differentiate between fat loss and muscle gain.
How to Use the Body Fat Calculator
Select your biological gender (the formula differs for men and women).
Enter your height and neck circumference.
Enter your waist circumference (and hip circumference for women).
Instantly view your estimated body fat percentage and category.
Frequently Asked Questions
It is widely considered accurate to within 3-4% of medical DEXA scans, making it one of the best accessible methods for home tracking.
Never. All calculations happen entirely in your browser memory. We have zero access to your inputs.
For men, measure horizontally around the navel. For women, measure at the narrowest point of the abdomen.
All file processing is performed locally in your web browser. We do not upload, store, or view your data.