Estimate your body fat percentage using the US Navy method based on waist, neck, and height measurements.
Using the US Navy circumference method. Take measurements in cm.
Body fat percentage represents the proportion of your total body weight that is fat tissue, compared to lean mass (muscle, bone, organs, and water). Unlike weight or BMI alone, body fat percentage gives a more direct picture of body composition — two people with the same weight and height can have very different body fat percentages depending on muscle mass.
This calculator uses the U.S. Navy method, which estimates body fat percentage from circumference measurements (neck, waist, and for women, hips) combined with height. This method was developed for military fitness assessments and has been validated against more precise laboratory methods like DEXA scans, with a typical margin of error of around 3-4 percentage points for most people.
General classifications used by organizations like the American Council on Exercise place "essential fat" (the minimum needed for basic physiological function) at around 2-5% for men and 10-13% for women — the higher essential fat in women relates to hormonal and reproductive functions. "Athletic" ranges are typically 6-13% for men and 14-20% for women. "Fitness" ranges extend to roughly 14-17% for men and 21-24% for women, while "average" ranges fall around 18-24% for men and 25-31% for women. These are general guidelines, and healthy ranges can vary based on age, genetics, and individual health status.
Body weight doesn't distinguish between fat and muscle. Someone who builds muscle while losing fat might see little change on the scale despite a meaningful improvement in body composition and health markers. Body fat percentage — tracked over time using a consistent method — provides a more meaningful picture of progress for those focused on changing body composition rather than just total weight.
While convenient and free, tape-measure methods are less precise than methods like DEXA scans, hydrostatic weighing, or air displacement plethysmography (Bod Pod), which are considered more accurate reference standards. Bioelectrical impedance scales (common in home smart scales) can also vary based on hydration status, time of day, and recent food or exercise. For tracking trends over time, consistency in measurement technique and timing matters more than absolute precision.
How often should I measure my body fat percentage? Every 4-8 weeks is generally sufficient to track meaningful trends, taking measurements at the same time of day and under similar conditions (such as first thing in the morning before eating or drinking).
Can body fat percentage be too low? Yes — falling below essential fat levels can disrupt hormone production, immune function, and in women, menstrual cycles. Very low body fat percentages are generally only appropriate for short competition periods for physique athletes, under professional guidance.
Why do men and women have different healthy ranges? Women naturally carry more essential fat due to reproductive biology, including hormone production and fat stores that support pregnancy and breastfeeding.