🏃 Body Fat Percentage Calculator
Estimate body fat percentage with just a tape measure — no scale required.
Our free Body Fat Calculator uses the US Navy formula — requiring only a tape measure — to estimate your body fat percentage. More informative than BMI because it measures body composition directly rather than just weight-to-height ratio.
US Navy Body Fat Formula
Women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
Measurements should be taken in centimeters or inches (our calculator accepts both). Take all measurements in the morning, standing relaxed, at the same time for consistency.
Measurement Guide
- Neck: Measure just below the larynx (Adam's apple), sloping slightly downward at the front. Keep the tape horizontal.
- Abdomen (men): Measure at the navel, relaxed (not sucked in). This is the narrowest point of the torso.
- Waist (women): Measure at the narrowest point, usually about 1 inch above the navel.
- Hip (women): Measure at the widest point of the hips/buttocks with feet together.
- Height: Stand barefoot, back against a wall, heels together.
Body Fat Percentage Categories
- Men — Essential fat: 2–5% (minimum for organ function)
- Men — Athletic: 6–13%
- Men — Fitness: 14–17%
- Men — Average: 18–24%
- Men — Obese: 25%+
- Women — Essential fat: 10–13%
- Women — Athletic: 14–20%
- Women — Fitness: 21–24%
- Women — Average: 25–31%
- Women — Obese: 32%+
Women naturally carry more essential fat than men due to hormonal and reproductive physiology. The higher baseline is normal and healthy, not excess fat.
Why Body Fat % Is More Useful Than BMI
BMI cannot distinguish muscle from fat. A 180 lb person who is 8% body fat (athlete) and a 180 lb person who is 30% body fat (sedentary) have identical BMIs but very different health profiles. Body fat percentage reveals the actual body composition — the information that matters for health risk and fitness goals.
🏃 Estimate your body fat percentage with our free Navy method calculator.
Open Body Fat Calculator →Frequently Asked Questions
How accurate is the Navy method?
The US Navy formula is accurate to within 2–4% for most people in normal fitness ranges. It is less accurate for very muscular individuals (tends to overestimate body fat) and very obese individuals. For precise measurements, DEXA scan (Dual-Energy X-ray Absorptiometry) is the gold standard but requires clinical equipment. The Navy method is excellent for tracking trends over time even if the absolute number has some error.
How often should I measure body fat?
Monthly measurements are ideal. Body fat changes slowly — daily or weekly measurements introduce too much noise from hydration levels, digestion, and measurement variability. Take measurements under consistent conditions (same time of day, same measuring tape, same person measuring) to maximize accuracy of trend tracking.