📊Body Fat Calculator Navy circumference body fat %, BMI, Deurenberg estimate — metric or imperial, ACE categories, reference chart. How To Use: Choose US/imperial or metric. Enter height, weight, age, gender, and circumferences (waist at navel, neck below larynx; women also hip at widest point). You get U.S. Navy body fat %, WHO BMI, a Deurenberg population estimate, lean mass, ACE-style category, and a scrollable reference chart. Why Use This Tool International-ready body fat calculator: standard Navy circumference math, dual units, cross-checks used in research and fitness worldwide—not a substitute for clinical testing.