The Body Composition Calculator estimates your body fat percentage and lean body mass based on measurements of your waist, neck, height, and for women, hip circumference. It uses the U.S. Navy Body Fat Formula, which provides a reliable and practical estimation of body composition without requiring specialized equipment. The results indicate how much of your body is composed of fat compared to lean tissue like muscles, bones, and organs. A healthy body composition reflects a good balance of fat and lean mass, helping assess fitness, track progress, and set realistic health or weight goals.