Estimate your body fat percentage using the US Navy circumference method, which needs only a tape measure rather than special equipment. Enter your height and neck and waist measurements (plus hips for women), and the calculator applies the Navy formula to estimate the share of your body weight that is fat. It also shows your estimated fat mass and lean mass if you enter your weight, and places you in a general category. This method is a convenient screening estimate and can be off by several points compared with a lab scan, so use it to track change over time rather than as an exact number. Take measurements consistently for the best trend. Everything is computed locally in your browser.