Body Fat Calculator — Free Online Tool
Calculate body fat percentage using the US Navy circumference method. Enter height, neck, and waist measurements (hip for women). Results show body fat %, lean mass %, and fitness category. More accurate than BMI alone for most adults.
100% client-side. No uploads. Your data never leaves your browser.
How to use Body Fat Calculator
- Select gender and enter height.
- Measure and enter neck and waist circumference.
- Women: also enter hip circumference.
- See body fat %, lean mass %, and fitness category.
Frequently Asked Questions
How accurate is this?
The US Navy method typically has ±3-4% accuracy compared to DEXA scans. It's reliable for tracking trends over time.
How do I measure correctly?
Measure neck at the narrowest point, waist at the narrowest point (above navel), and hip (women only) at the widest point.
What is lean mass %?
Lean mass = 100% − body fat %. It includes muscle, bone, water, and organ tissue.
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