You can calculate your * Body Mass Index (BMI), * Body Fat Percentage (BFP) * Waist to Height Ratio(WHeR) * Waist to Hip Ratio (WHiR) with this app. The Body Fat Percentage, Calculator uses the U.S. Navy fitness formula to calculate an estimation of body fat. Although the water displacement test is the most accurate way to determine body fat percent, however the Navy Body Fat test or YMCA formula is sufficiently accurate within 1-3% for most people.