Estimate your body fat percentage using the U.S. Navy method.
This calculator uses the U.S. Navy body fat estimation method, developed by Hodgdon and Beckett at the Naval Health Research Center. It uses circumference measurements of the neck and waist (plus hips for women) along with height to estimate body fat percentage. The method was validated against hydrostatic (underwater) weighing and has been shown to be accurate within 3-4% for most people.
Neck: Measure at the narrowest point, just below the Adam's apple. Keep the tape level and snug but not tight. Waist: Measure at the narrowest point of your torso, typically at the navel for men and at the natural waistline for women. Stand relaxed and do not suck in your stomach. Hips (women only): Measure at the widest point of the hips and buttocks. For best accuracy, take each measurement three times and use the average.
The American Council on Exercise (ACE) provides the following body fat categories. For men: essential fat is 2-5%, athletes 6-13%, fitness 14-17%, acceptable 18-24%, and obese 25%+. For women: essential fat is 10-13%, athletes 14-20%, fitness 21-24%, acceptable 25-31%, and obese 32%+. Women naturally carry more essential body fat than men due to hormonal differences and reproductive function. Essential fat is the minimum required for basic physiological function, and dropping below these levels is dangerous.
Body fat percentage is a more accurate indicator of health risk than BMI because it directly measures fat rather than inferring it from height and weight. Two people can have identical BMIs but very different body fat percentages. A muscular person with a BMI of 28 and 15% body fat is metabolically healthy, while a sedentary person with a BMI of 28 and 32% body fat faces significantly higher health risks. The BMI Calculator is a useful screening tool, but body fat percentage provides a clearer picture.
Reducing body fat requires a sustained calorie deficit combined with exercise that preserves muscle mass. The most effective approach includes resistance training at least 2-3 times per week (to maintain muscle during weight loss), a moderate calorie deficit of 500 calories per day (use the Calorie Calculator to find your target), and adequate protein intake of 0.7-1.0 grams per pound of body weight. Cardio helps create a larger deficit but should not replace resistance training. Crash diets and extreme deficits tend to cause muscle loss alongside fat loss, which worsens body composition even if the scale number drops.
The Navy method used in this calculator measures your neck, waist, and hips (women only) to estimate body fat percentage. It's accurate to within 3-4% for most people, which is good enough for tracking trends over time. The key is measuring consistently: same spots, same tension on the tape, same time of day.
Healthy body fat ranges are roughly 14-24% for men and 21-31% for women, with the ranges shifting higher as you age. Athletes and serious exercisers often fall below these ranges. For more detail on what different body fat percentages look like and which measurement methods are most accurate, see our complete body fat percentage guide.