Body Fat % Calculator: Estimate Your Body Fat Using the U.S. Navy Method

Your body fat percentage tells you how much of your weight is fat versus lean mass (muscle, bone, organs, water), which is a far more accurate picture of fitness than weight or BMI alone. This calculator uses the U.S. Navy Method, a circumference-based formula originally developed by the U.S. Navy to estimate body composition quickly using just a tape measure, no calipers or expensive body scans required. It remains one of the most widely validated field methods for estimating body fat percentage today. If you have not already, check your BMI and Ideal Weight for more context on your overall body composition.

How This Calculator Works

This calculator uses the U.S. Navy circumference method, the same field-tested formula the U.S. Navy uses for fitness assessments. It estimates body fat percentage from your height, neck, and waist measurements (plus hip measurement for women), using only a tape measure. While it is not as precise as a DEXA scan or hydrostatic weighing, it is significantly more accessible and has been shown in research to be reasonably accurate for most body types, making it one of the best free options available without special equipment.

For the most accurate reading, measure your neck just below the larynx, your waist at the navel while relaxed (not sucked in), and, for women, your hip at the widest point. Measure in the morning before eating for the most consistent results over time.

Understanding Your Body Fat Category

Body fat percentage categories differ between men and women because women naturally carry more essential fat to support reproductive health. The table below, based on the American Council on Exercise (ACE) classification, shows how the ranges compare.

Body Fat % vs. BMI: Why It Matters

BMI only looks at your height and weight, so it cannot tell the difference between muscle and fat. Two people with the same BMI can have very different body compositions, one lean and muscular, the other with a higher fat percentage. Body fat percentage fills that gap, giving you a clearer sense of what your weight is actually made of. For a complete picture, pair this result with our BMI Calculator and TDEE Calculator to plan your calorie and macro targets around your goal.

Disclaimer: This calculator provides an estimate based on the U.S. Navy circumference method and population averages. It is not a substitute for professional medical assessment. Individual body composition can vary; consult a healthcare provider or registered dietitian for personalized guidance.