Body Fat Calculator

Body Fat Categories

How accurate is the US Navy body fat formula?

The US Navy circumference method has a margin of error of approximately 3–4 percentage points compared to DEXA scans (the gold standard). It works best for people with average body proportions. Sources of inaccuracy include measurement technique (measuring tape tension, location on body) and unusual fat distribution patterns. Take multiple measurements and average them for better accuracy.

What is a healthy body fat percentage for athletes?

Athletic body fat ranges: Men — Essential fat is 2–5%, Athletic is 6–13%, Fitness is 14–17%, Acceptable is 18–24%. Women — Essential is 10–13%, Athletic is 14–20%, Fitness is 21–24%, Acceptable is 25–31%. Most endurance athletes perform best in the athletic range. Going below essential fat levels impairs hormone function and increases injury risk.

How do I measure correctly for the Navy method?

Waist: measure at the narrowest point (or at the navel for the Navy method), standing relaxed — do not suck in. Neck: measure just below the larynx (Adam's apple), tilting chin slightly up. Hip (women): measure at the widest point around the glutes. Use a flexible measuring tape kept horizontal, snug but not compressing skin. Take 2–3 readings and average.

What is the difference between body fat measurement methods?

DEXA scan: most accurate (~1–2% error), uses X-ray to distinguish bone, muscle, and fat. Hydrostatic weighing: very accurate but requires full submersion in water. BodPod: air displacement, accurate and non-invasive. Skinfold calipers: accurate in trained hands (~3–4% error). Bioelectrical impedance (smart scales): convenient but affected by hydration, meals, and exercise (~4–6% error). Navy method: free and practical (~3–4% error).

How does body fat affect athletic performance?

Excess body fat increases the weight you carry without contributing to power output, reducing performance in any gravity-dependent sport (running, climbing, cycling uphill). However, very low body fat impairs hormone production, immune function, and bone density. There is a performance sweet spot for each sport and individual. Dropping body fat too aggressively also risks muscle loss and fatigue.