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Body Fat Calculator

Estimate your body fat percentage using the US Navy method. Requires simple body measurements.

💡 Measure at the widest point. For waist/abdomen, measure at the navel level.

Body Fat Results

About the Body Fat Calculator

This calculator uses the US Navy method, a widely accepted non-invasive technique for estimating body fat percentage. It requires only a measuring tape and body circumference measurements.

How to Use

  1. Select your gender and preferred unit (inches or centimeters).
  2. Enter your height and optionally your weight (for lean/fat mass calculations).
  3. Enter your neck and waist/abdomen circumference. Women also enter hip circumference.
  4. All measurements should be taken at the widest points. Waist is measured at the navel.
  5. Click Calculate Body Fat.

How It Works — US Navy Formula

Men: BF% = 86.010 × log₁₀(abdomen − neck) − 70.041 × log₁₀(height) + 36.76

Women: BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387

Example

Male: Height 70", Neck 15", Waist 34":
BF% = 86.010 × log₁₀(34−15) − 70.041 × log₁₀(70) + 36.76 = ~18.5%

Frequently Asked Questions

The US Navy method has a margin of error of approximately ±3–4% compared to DEXA scans (the gold standard). It's suitable for tracking trends over time but less accurate than clinical methods.
Men: Essential fat 2–5%, Athletes 6–13%, Fitness 14–17%, Average 18–24%, Obese 25%+. Women: Essential fat 10–13%, Athletes 14–20%, Fitness 21–24%, Average 25–31%, Obese 32%+.
For the US Navy method, waist is measured at the navel (belly button). Measure while relaxed, not while sucking in your stomach.