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.
How to Use the Body Fat Calculator
Select your Gender from the dropdown.
Enter your Height (cm), Neck Circumference (cm), and Waist Circumference (cm).
If you selected female, also enter your Hip Circumference (cm).
Click "Calculate Body Fat" to see your estimated body fat percentage and category.
Frequently Asked Questions
This calculator uses the U.S. Navy method. For men: %BF = 495 / (1.0324 - 0.19077×log10(waist-neck) + 0.15456×log10(height)) - 450. For women, it also factors in hip circumference: %BF = 495 / (1.29579 - 0.35004×log10(waist+hip-neck) + 0.22100×log10(height)) - 450.
The U.S. Navy formula for women includes hip circumference because body fat distribution differs between men and women, so the hip field only appears when "Female" is selected.
The formula requires waist (plus hip for women) minus neck to be a positive number. If your measurements produce a zero or negative value, the calculator shows an "Invalid input!" message since the result would be mathematically undefined.
The categories (Essential Fat, Athletes, Fitness, Average, Obese) follow common U.S. Navy method ranges and are for general informational purposes only. Measurement technique affects accuracy, so treat the result as an estimate rather than a clinical measurement.